The Pope is personally investigating claims that Britain's most senior Roman Catholic was involved in "inappropriate" acts with priests.
Cardinal Keith O'Brien, who was born in Co Antrim and is the leader of the church in Scotland, was under mounting pressure to stand aside from taking part in the vote next month to elect Benedict XVI's successor.
The cardinal, the only British cleric who will have a say in choosing the new Pope, contests the claims and is said to be taking legal advice.
Yesterday, church leaders acknowledged doubts over his participation in the vote but insisted the decision was in his hands. Vatican officials have been attempting to dampen speculation that the Pope's resignation could be linked to a secret dossier of information on the Vatileaks scandal.
Over the weekend, the Vatican's secretary of state, Cardinal Tarcisio Bertone, issued a denunciation of the "unverified, unverifiable, or even completely false" claims.
But even as Cardinal Bertone spoke, 'The Observer' published allegations from four men – three priests and one former priest – of "inappropriate" behaviour by Cardinal O'Brien dating back as far as 1980. One priest alleges that he received unwanted attention from the cardinal after a late-night drinking session.
Cardinal O'Brien, who turns 75 next month, pulled out of leading a Mass to honour Pope Benedict in Edinburgh yesterday.
The Rt Rev Stephen Robson, the auxiliary bishop in the diocese, visited Cardinal O'Brien yesterday and left saying: "He is very upset, he is bound to be."
But when asked whether the cardinal would still be going to Rome, where he is expected on Tuesday, he said only that a statement would be released soon. Cardinal Cormac Murphy-O'Connor, the former Archbishop of Westminster, said he was saddened by the claims. But he insisted: "The allegations have not been proved in any way, so he will have to decide whether he wants to go."
Last night it emerged that the Pope was examining the allegations. (© Daily Telegraph, London)