The cardinal who until recently served as Britain's highest-ranking Catholic leader has acknowledged having engaged in unspecified sexual misbehaviour and promised to play "no further part" in the public life of the church, a statement that comes at an awkward time for the Vatican.

Cardinal Keith O'Brien resigned last week from his position as archbishop of St Andrews and Edinburgh after a newspaper published unnamed priests' accounts of unspecified inappropriate behaviour.

O'Brien initially rejected the claims, saying he was resigning because he did not want to distract from the upcoming conclave of cardinals that is due to pick a successor to Benedict XVI, who resigned the papacy last week. O'Brien also said he would not attend the conclave.

But on Sunday (local time), the Catholic church in Scotland issued a statement quoting O'Brien as saying that there had been times "that my sexual conduct has fallen below the standards expected of me as a priest, archbishop and cardinal".

"To those I have offended, I apologise and ask forgiveness," the statement continued. "To the Catholic church and people of Scotland, I also apologise. I will now spend the rest of my life in retirement. I will play no further part in the public life of the Catholic church in Scotland."

O'Brien gave no clue as to what exactly his sexual misbehaviour consisted of, but his statement is nonetheless another reminder of the church's struggle shake off a litany of sex scandals, including those involving paedophile priests.

The claims against O'Brien were first reported by The Observer newspaper.

In its February 24 edition, the British newspaper reported that O'Brien was alleged to have made what it described as "an inappropriate approach" to a seminarian after night prayers.

The paper also said another priest had reported "inappropriate contact" with O'Brien following a visit to his parish, a second priest had reported "unwanted behaviour" by the archbishop following a late-night drinking session, and that a third had reported being taken advantage of when he went to the archbishop for counselling.

All four, the paper said, had sent letter of complaint to nuncio Antonio Mennini, the Vatican's ambassador to Britain, early last month.

The paper did not cite a source for its reporting last week, but in this Sunday's edition it quoted the still-unnamed former seminarian as saying that the church had failed to respond quickly and appropriately to his complaint.

O'Brien has at times had a rocky tenure as a cardinal.

In 2003, as a condition of assuming that rank, he was forced to issue a public pledge to defend church teaching on homosexuality, celibacy and contraception. He was pressured to make the pledge after he had called for a "full and open discussion" on such matters.

At the time, O'Brien said he had been misunderstood and wanted to clarify his position. But statements made last week, before the scandal over his behaviour broke, suggested he never really changed his mind.

In an interview with the BBC, O'Brien said celibacy should be reconsidered because it's not based on doctrine but rather church tradition and "is not of divine origin".

- AP