LONDON — A Roman Catholic cardinal who resigned as head of the church in Scotland apologized on Sunday for sexual conduct which he said had "fallen below the standards expected of me."

Cardinal Keith O'Brien was Britain's most senior Catholic cleric until he resigned as archbishop on Feb. 25 and said he would not take part in the conclave to elect a new pope. The announcement followed newspaper allegations of inappropriate behavior with priests.

"I wish to take this opportunity to admit that there have been times that my sexual conduct has fallen below the standards expected of me as a priest, archbishop and cardinal," he said in a statement posted on the Scottish Catholic media office website on Sunday.

"To those I have offended, I apologize and ask forgiveness. To the Catholic Church and people of Scotland, I also apologize. I will now spend the rest of my life in retirement," O'Brien said. "I will play no further part in the public life of the Catholic Church in Scotland."

O'Brien's resignation as archbishop of St. Andrews and Edinburgh was announced a day after the Observer newspaper reported that three priests and one former priest from a Scottish diocese had complained over incidents dating back to the 1980s.

The Observer said O'Brien, an outspoken opponent of moves in Britain to legalize gay marriage, had been reported to the Vatican over the unspecified incidents.

The cardinal initially rejected the allegations and said he was seeking legal advice. He ruled himself out of the conclave to avoid focusing media attention on himself.

Last year, O'Brien's comments labeling gay marriage "a grotesque subversion" landed him with a "Bigot of the Year" award from gay rights group Stonewall.

O'Brien's dramatic resignation and self-exclusion from the conclave added to a sense of crisis in the Catholic Church as it deals with the resignation of Pope Benedict against a backdrop of scandals.

O'Brien would have been Britain's only elector at the conclave. He could have attended despite his resignation as archbishop, but chose not to do so.

Benedict's papacy, which ended on Thursday when he flew away from the Vatican by helicopter, was rocked by scandals over the sexual abuse of children by priests.