Beirut (AFP) - The Islamic State group released a video Tuesday purportedly showing a captive Jordanian fighter pilot being burned alive, in the jihadists' most brutal execution yet of a foreign hostage.

The highly produced 22-minute video released online showed images of a man purported to be First Lieutenant Maaz al-Kassasbeh, who was captured in December, engulfed in flames inside a metal cage.

Amman confirmed the death of the 26-year-old, while the video's authenticity has still not been verified, and vowed an "earth-shattering" response.

The military warned that "the blood of the martyr will not have been in shed in vain and... vengeance will be proportional to this catastrophe that has struck all Jordanians".

State television said Kassasbeh had been killed January 3, before IS offered to spare his life and free a Japanese journalist in return for the release of a female would-be suicide bomber on death row in Jordan.

A security official said the woman, Iraqi Sajida al-Rishawi would be executed at dawn Wednesday.

US President Barack Obama immediately denounced the killing.

"Should in fact this video be authentic, it's just one more indication of the viciousness (and) barbarity of this organisation," Obama said of IS.

The United States will "redouble the vigilance and determination on the part of the global coalition to make sure" the group is "ultimately defeated", he added.

The White House said US intelligence was working to confirm the video's authenticity.

- 'Barbaric enemy' -

The chief of the US-led war on IS, General Lloyd Austin, condemned the pilot's murder as "savage" and vowed to "fight this barbaric enemy until it is defeated".

British Prime Minister David Cameron said the "sickening murder will only strengthen our resolve to defeat ISIL", another acronym for the group.

Kassasbeh was captured on December 24 after his F-16 jet crashed while on a mission over northern Syria as part of the US-led coalition campaign against the jihadists.

The video released Tuesday shows footage of him at a table recounting coalition operations against IS, with flags from the various Western and Arab countries in the alliance projected in the background.

It then shows Kassasbeh dressed in an orange jumpsuit and surrounded by armed and masked IS fighters in camouflage.

It cuts to him standing inside the cage and apparently soaked in petrol before a masked jihadist uses a torch to light a trail of flame that runs to the cage and burns him alive.

The release of the video of the pilot's purported murder came days after IS beheaded a second Japanese hostage within a week.

- 'Horrific, disgusting' footage -

Shiraz Maher, from the International Centre for the Study of Radicalisation at King's College London, described the footage as "simply the most horrific, disgusting thing I have seen from Islamic State in the last two years".

"They clearly want to make a real point. This is the first individual whom they have captured who has been directly involved with the Western coalition in fighting IS. It is different from the aid workers... This is an act of belligerence".

"Every time you think they cannot commit anything worse -- they open up another trapdoor."

IS had vowed to kill the second Japanese, Kenji Goto, and Kassasbeh by sunset on January 29 unless Amman handed over Iraqi jihadist and Rishawi.

Kassasbeh's plane was the first loss of an aircraft since the coalition launched strikes against IS last year.

Along with Jordan, Saudi Arabia, the United Arab Emirates and Bahrain are taking part in the coalition air strikes in Syria. Australia, Belgium, Britain, Canada, Denmark, France and the Netherlands are participating in Iraq.

The extremist group seized swathes of territory in Iraq and Syria last year, declaring an Islamic "caliphate" and committing a wave of atrocities.

IS claimed in a video released Saturday that it had killed 47-year-old Goto, after previously murdering another Japanese hostage, Haruna Yukawa.

The group had initially demanded a $200 million (175 million euro) ransom for the Japanese hostages -- the same amount Tokyo had promised in non-military aid to countries affected by IS.

It had previously beheaded two US journalists, an American aid worker and two British aid workers in similar highly choreographed videos.

Jordan had vowed to do everything it could to save the pilot but had demanded proof he was still alive before handing over Rishawi.

IS had previously published what it said was an interview with the pilot in which he said his plane was hit by a heat-seeking missile.

IS claimed to have shot down his plane but both Jordan and the United States said it had crashed.

Kassasbeh's family had urged IS to release the recently married pilot, with his father Safi asking the jihadist group to show "mercy".

After the killing of Goto, the UN Security Council condemned the "heinous and cowardly" murder, calling for "the immediate, safe and unconditional release of all those who are kept hostage" by the group.

New IS video purportedly shows hostage's murder

Jordanian pilot Muath al-Kasaesbeh was taken captive by the militant group after his jet crashed in Syria.
State TV: Killed on Jan. 3

ARTEMIVSK, Ukraine (AP) — The United Nations on Tuesday sharply criticized both the Ukrainian government and the pro-Russian rebels for turning bus stops, schools, markets and hospitals into battlegrounds where civilians are getting killed.

Indiscriminate shelling and an escalation in the fighting in eastern Ukraine have killed at least 224 civilians in the past three weeks alone, the U.N. said, raising the overall death toll to 5,358 people since April.

Hostilities between Russian-backed separatists and Ukrainian troops resumed with a vengeance in January after a month of relative calm. The latest peace talks broke down Saturday, with both sides blaming the other for prolonging the fighting.

"Bus stops and public transport, marketplaces, schools and kindergartens, hospitals and residential areas have become battlegrounds ... in clear breach of international humanitarian law," U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein said, adding that 545 civilians were wounded in the last three weeks as well.

He blamed the high civilian death toll on "the indiscriminate shelling of residential areas in both government-controlled territory and in areas controlled by the armed groups."

Rebels in the separatist stronghold of Donetsk said Tuesday that artillery fire killed at least eight people and wounded 22 others in the past day, while Ukrainian military spokesman Andriy Lysenko said five servicemen had been killed and 27 wounded in the same period.

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A firefighter works on the top of a house, which according to locals was recently damaged by shellin …

The rebels' main offensive is now directed at Debaltseve, a railway junction between the rebel-held cities of Luhansk and Donetsk. Separatists say they are not planning to storm Debaltseve itself because of the potential for civilian casualties.

Ukraine accuses Russia of arming the rebels, a charge that Russia denies. But Western military experts say the sheer amount of heavy weapons in rebel hands belies that denial.

President Barack Obama has so far opposed sending lethal assistance to aid Ukraine's government, but a senior administration official told The Associated Press the surge in fighting has spurred the White House to review that policy.

But German Chancellor Angela Merkel reiterated Tuesday in Berlin that Germany would not deliver lethal weapons to Ukraine, saying she intends to focus on finding a "diplomatic solution" to the conflict.

Ukrainian Prime Minister Arseniy Yatsenyuk, meanwhile, signed a decree abolishing national ID travel between Ukraine and Russia, saying Ukraine needed to tighten its controls along the border.

___

Yuras Karmanau in Kiev, Ukraine, Frank Jordans in Berlin and Lynn Berry and Nataliya Vasilyeva in Moscow contributed to this report.

Related video:

Amman (AFP) - Jordan will execute Wednesday an Iraqi would-be suicide bomber on death row and other jihadists after having vowed to avenge the murder of a Jordanian pilot by Islamic State jihadists, an official said.

"The sentence of death pending on... Iraqi Sajida al-Rishawi will be carried out at dawn," the security official said on Tuesday, speaking on condition of anonymity.

Rishawi, the would-be bomber, was condemned to death for her participation in deadly attacks in Amman in 2005, and IS had offered to spare the life of the Jordanian fighter pilot, Lieutenant Maaz al-Kassasbeh, if she were released.

"The death sentence will be carried out on a group of jihadists, starting with Rishawi, as well as Iraqi Al-Qaeda operative Ziad Karbuli and others who attacked Jordan's interests," the security source said.

"Jordan's response will be earth-shattering," Information Minister Mohammed Momani said earlier on television, while the army and government vowed to avenge the pilot's murder.

"Whoever doubted the unity of the Jordanian people, we will prove them wrong," said Momani, who is also government spokesman.

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A screengrab from an ISIS video reporting to show Jordanian Pilot Muath al-Kasasba prior to being bu …

"The pilot did not belong to a specific tribe or come from a specific governorate, he was the son of all Jordanians, who stand united," he said.

State television also reported that King Abdullah II of Jordan would cut short a visit to Washington and return home in the wake of the pilot's murder.

The king had held talks with US Secretary of State John Kerry in Washington on Tuesday before going into a meeting with the Senate Foreign Relations Committee on Capitol Hill.

One of America's most stalwart allies in the Middle East, Jordan is taking part in US-led air strikes against the Islamic State group in Syria along with several other Arab countries.

Related video:

Argentina's President Cristina Fernandez de Kirchner gestures during a meeting with governors in Casa Rosada government house in Buenos Aires January 30, 2015. REUTERS/Enrique Marcarian

BUENOS AIRES (Reuters) - An Argentine prosecutor found dead in mysterious circumstances last month had drafted a request that President Cristina Fernandez be arrested for conspiring to derail his probe into the deadly bombing of a Jewish center, the investigator into his death said on Tuesday.

The papers were found in the trash at Alberto Nisman's apartment while his property was being scoured for clues over whether the father-of-two committed suicide or was murdered.

He was found in a pool of blood with a single bullet to the head on Jan. 18.

"The drafts are in the file," Viviana Fein, the lead investigator into Nisman's death, told a local radio station.

The request for Fernandez's arrest, which the prominent pro-opposition daily newspaper Clarin said Nisman drafted in June, was not included in his final 350-page submission to the judiciary delivered days before his death. Instead Nisman called for Fernandez to face questions in court.

On Monday, Fein's office had denied the existence of the document containing the arrest request and the government denounced a Clarin story about it as "garbage".

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Argentine prosecutor Alberto Nisman, who is investigating the 1994 car-bomb attack on the Argentine …

Cabinet Chief Jorge Capitanich even dramatically tore up a copy of the paper in his daily news briefing. But on Tuesday, Fein backtracked, saying there had been a misunderstanding between her and her office, and the documents did exist.

"They are properly incorporated into the case file, nothing is missing," Fein said of the papers on Tuesday.

Nisman spent almost a decade building up a case that Iran was behind the 1994 attack on the Argentine Israelite Mutual Association (AMIA) that killed 85 people. Iran's government has repeatedly denied the allegation.

Nisman had been due the day after his death to answer questions in Congress about his allegations that Fernandez sought to cover up Iran's involvement in return for Iranian oil. Fernandez has called the claim "absurd".

Argentine judges are proving reluctant to take on a case some are calling a "judicial hot potato". Two judges turned down hearing the case on Monday, including one who is already presiding over separate charges of attempts to derail the investigation into the 1994 bombing.

The other cover-up charges involve ex-President Carlos Menem, who ruled the South American country from 1989 to 1999.

Fernandez, who had come under fierce criticism for her handling of Nisman's death, is currently on a trip to China.

(Reporting by Richard Lough and Sarah Marsh; Editing by Will Dunham, Kieran Murray, Toni Reinhold)

Up to 10 million gallons (38 million liters) of crude oil from the 2010 Deepwater Horizon oil spill has settled at the bottom of the Gulf of Mexico, where it is threatening wildlife and marine ecosystems, according to a new study.

The finding helps solve the mystery ofwhere the "missing" oil from the spill landed. Its location had eluded both the U.S. government and BP cleanup crews after the April 2010 disaster that caused about 200 million gallons (757 million liters) of crude oil to leak into the Gulf.

"This is going to affect the Gulf for years to come," Jeff Chanton, the study's lead researcher and a professor of chemical oceanography at Florida State University, said in a statement. "Fish will likely ingest contaminants because worms ingest the sediment, and fish eat the worms. It's a conduit for contamination into the food web." [Deepwater Horizon: Images of an Impact]

The researchers took 62 sediment cores from an area encompassing 9,266 square miles (24,000 square kilometers) around the site of the Deepwater Horizon spill. Unlike other sediment on the ocean floor, oil does not contain any carbon-14, a radioactive isotope. Therefore, sediment samples without carbon-14 indicate that oil is present, Chanton said.

The scientists avoided areas with natural oil seeps, features in which oil slowly leaks onto the ocean floor through a series of cracks. In these areas, the sediment cores would have a lack of carbon-14 throughout the sample. In areas that don't normally have oil, "the oil is just in the surficial layer, like in that 0 to 1 centimeter [0 to 0.39 inches]" interval," Chanton told Live Science.

After studying the samples, the researchers made a map of the areas affected by the spill. About 3,243 square miles (8,400 square km) are covered with oil from the Deepwater Horizon spill, they found.

It's unclear exactly how the oil got there after the spill. One idea is that the oil particles clumped together at the water's surface, or in plumes from the underwater leak, and became heavy enough to sink to the bottom of the Gulf. Cleanup crews also burned large patches of oil, and the resulting black carbon and ash could have sunk into the water, the researchers said. Or, zooplankton (tiny animals that drift near the water's surface) may have ingested the oil and discarded it in fecal pellets that sank to the Gulf floor, the researchers added.

For now, the sunken oil may help keep the water above it clear and free of black oil particles, Chanton said, but it's turning into a long-term problem.

"There's less oxygen down there, and so that will slow the decomposition rate of the oil," Chanton said. "It might be there for a long period of time, a little reservoir of contamination." Moreover, the oil may cause tumors and lesions on underwater animals, research suggests.

The new study supports the findings of another independent study, which found that about 10 percent of the spill's oil made it to the Gulf floor. Using hopane, a hydrocarbon found in oil, the researchers of that study, published in the journal Proceedings of the National Academy of Sciences in October 2014, analyzed sediment samples to see how much oil had fallen to the bottom of the Gulf.

The new study calculates that 3 to 5 percent of the oil from the spill sank to the ocean floor, but the results of the two studies aren't that different, Chanton said.

"Our number is a little bit more conservative than theirs," he said, but "if the two approaches agree within a factor of two, that's pretty good for estimating all of the oil on the seafloor."

The findings were published Jan. 20 in the journal Environmental Science & Technology.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience,Facebook & Google+. Original article on Live Science.