LONDON -- The Vatican is looking into allegations of "inappropriate behaviour" by Cardinal Keith O'Brien, Britain's most senior Catholic cleric, officials said Sunday. The claims came at a sensitive time, as O'Brien and other cardinals prepare for a conclave to choose the next pope.

O'Brien, who heads the Roman Catholic Church in Scotland, was taking advice from lawyers after British newspaper The Observer reported that three priests and a former priest have filed complaints to the Vatican alleging that the cardinal approached them in an inappropriate manner.

The paper did not cite the names of the priests, but it said their allegations date back to the 1980s.

"Cardinal O'Brien contests these claims and is taking legal advice," Peter Kearney, a spokesman for the Scottish Catholic Church, said. He declined to comment further.

A Vatican spokesman, the Rev. Federico Lombardi, said the complaints had been channeled through the office of the papal nuncio -- the Vatican's ambassador -- in London. "The pope has been informed, and the question is in his hands," Lombardi said.

In the coming weeks, O'Brien, 74, is expected to join a conclave of cardinals at the Vatican to elect the next pontiff, following the resignation of Pope Benedict XVI. Benedict announced earlier this month that he will step down on Thursday -- the first pope to resign in some 600 years.

O'Brien has not been the only cardinal to become embroiled in negative news as the papal election approaches. Across the Atlantic, thousands of people have signed a petition to keep California Cardinal Roger Mahony from the conclave because of revelations he had shielded sexually abusive priests.

Mahony has made it clear he will attend the gathering and that no one can force him to recuse himself.

In comments on the papacy made to the BBC on Friday, O'Brien said the next pope would be free to consider changing church policy on issues that were not "basic dogmatic beliefs." He said he believed that the requirement for priestly celibacy is not "of divine origin" and could be reconsidered.

O'Brien also said it was time to think seriously about having a pope from outside Europe. He said he would be "open to a pope from anywhere if I thought it was the right man, whether it was Europe or Asia or Africa or wherever."

The cardinal is due to retire when he turns 75 in March.