VATICAN CITY (Reuters) - Pope Benedict will see out his life in prayer, "hidden from the world", he said on Thursday in his first personal comment on his plans since he stunned Roman Catholics by announcing his retirement.

His remarks, in a voice that was hoarse at times, followed Monday's resignation notice which spoke of "a life dedicated to prayer"; the Vatican has said the 85-year-old German will live within its walls. His seclusion may allay concern that the first living former pope in centuries might trouble Church unity.

Speaking unscripted to thousands of priests from the diocese of Rome, in what turned out to be a farewell address in his capacity as bishop of the Italian capital, Benedict outlined a cloistered life ahead, once he steps down in two weeks time:

"Even if I am withdrawing into prayer, I will always be close to all of you and I am sure that you will be close to me, even if I remain hidden to the world," he said.

After February 28, when he becomes the first pontiff in hundreds of years to resign instead of ruling for life, Benedict will first go to the papal summer retreat at Castel Gandolfo, south of Rome, and then move permanently into the four-storey Mater Ecclesiae convent, in the gardens behind St. Peter's Basilica.

The Vatican has already said that he will not influence the election of his successor, which will take place in a secret conclave to start between March 15 and 20 in the Sistine Chapel.

But his unprepared comments to his priests at the emotional meeting in the Vatican's modern audience hall was the first time the pope had spoken specifically in public about how he will spend his time after his resignation.

The Vatican, which is navigating uncharted waters since his shock announcement, said experts have still not decided what his title will be or whether he will wear the white of a pope, the red of a cardinal or the black of an ordinary priest.

"In my opinion, once he resigns he should put aside the white cassock and put on the robes of a cardinal," said Father Thomas Reese, senior fellow at the Woodstock Theological Center at Georgetown University and an author of books on the Vatican.

"He should no longer be called pope, or Benedict, or your Holiness, but should be referred to as Cardinal Joseph Ratzinger," Reese added. "After the new pope is elected, he should attend his installation along with the other retired cardinals and pledge his allegiance to the new pope."

Thursday's meeting with priests was the latest event in what has become a slow-motion, long goodbye to the man who has led the 1.2 billion-strong Roman Catholic Church for eight years.

On Wednesday night, he presided at an Ash Wednesday Mass that was moved to the vast St Peter's Basilica from its original venue in Rome.

A capacity crowd gave him a thunderous standing ovation at his last public Mass. In his homily he said the Church had been at times "defaced" by scandals, divisions and rivalries.

"Thank you. Now, let's return to prayer," the pontiff said, bringing an end to several minutes of applause that clearly moved him. In an unusual gesture, bishops took off their mitres in a sign of respect. Some of them wept.

One of the priests at the altar, which according to tradition rests above the tomb of St. Peter, took out a handkerchief to dry his tears.

SCANDAL, DIVISIONS AND RIVALRIES

The Wednesday night homily appeared to be one of his last testaments to a Church has been shaken by scandals around the world and closer to home.

Benedict's papacy was rocked by crises over the sexual abuse of children by priests in Europe and the United States, most of which preceded his time in office but came to light during it.

His reign also saw Muslim anger after he compared Islam with violence. Jews were upset over the rehabilitation of a Holocaust denier. During a scandal over the Church's business dealings, his butler was accused of leaking his private papers.

The Vatican said 117 cardinals will be eligible to enter the March conclave to choose Benedict's successor. Cardinals lose their right to elect a new pope if they turn 80 before the See of St. Peter becomes vacant, as it will on February 28.

Benedict's message to his flock since his announcement has been that the Church is bigger than any human being, including the pope, and will not be hurt by his resignation for health reasons.

He said on Wednesday he was sustained by the "certainty that the Church belongs to Christ, who will never stop guiding it and caring for it" and suggested that the faithful should also feel comforted by this.

Cardinals around the world have already begun informal consultations by phone and email to construct a profile of the man they think would be best suited to lead the Church in a period of continuing crisis.

The conservative Benedict has appointed more than half of the cardinals who will elect his successor so it is unlikely the new man will tamper with any teachings such as the ban on artificial birth control or women priests.

But many in the Church have been calling for the election of someone who they say will be a better listener to other opinions within the Church.

The likelihood that the next pope would be a younger man and perhaps a non-Italian, was increasing, particularly because of the many mishaps caused by Benedict's mostly Italian top aides.

(Editing by Alastair Macdonald)

LONDON (Reuters) - Britain's Food Standards Agency (FSA) said six horses slaughtered in the UK that tested positive for the drug phenylbutazone were exported to France and may have entered thehuman food chain.

Phenylbutazone, commonly known as bute, is an anti-inflammatory painkiller for sporting horses but banned for animals intended for eventual human consumption as it is potentially harmful.

Britain's food regulator said on Thursday it was gathering information on the six carcasses sent to France and will work with the French authorities to trace them.

The FSA said it checked 206 horse carcasses between January 30 and February 7. Of these, eight tested positive for the drug.

It said the six sent to France were slaughtered by LJ Potter Partners at Stillman's (Somerset) Ltd in Taunton, western England.

The remaining two did not leave the slaughterhouse in the UK -High Peak Meat Exports Ltd, Nantwich, north west England - and have now been disposed of.

The FSA introduced 100 percent testing of horse carcasses on January 30 in response to the growinghorse scandal.

The issue first came to light on January 15 when routine tests by Irish authorities discovered horsemeat in beef burgers made by firms in Ireland and Britain and sold in supermarket chains including Tesco, Britain's biggest retailer.

Concern grew last week when the British unit of frozen foods group Findus began recalling its beef lasagne on advice from its French supplier, Comigel, after tests showed concentrations of horsemeat ranging from 60 to 100 percent.

The revelations, affecting a growing number of countries, processors and retailers, have raised uncomfortable questions about the safety of the European food supply chain and prompted governments to send out a European Union-wide alert.

Earlier on Thursday a British parliamentary report into the scandal said discoveries so far of horsemeat in products sold as beef are likely to be the "tip of the iceberg".

(Reporting by James Davey; editing by Neil Maidment)