The cardinal, who was Britain's most senior Catholic cleric, stepped down from his post as Archbishop of St Andrews and Edinburgh last week, a day after three priests and a former priest made allegations of "inappropriate" behaviour against him.

In a statement issued by the Catholic Church in Scotland last night, he apologised and asked forgiveness from those he had "offended".

"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," the statement said.

Cardinal O'Brien said he will spend the rest of his life in retirement and will play no further part in the public life of the Catholic Church in Scotland.

It is understood he is currently out of the country and will not be attending the Conclave to elect the successor to Pope Benedict.

The statement said: "In recent days certain allegations which have been made against me have become public. Initially, their anonymous and non-specific nature led me to contest them.

"However, 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.

"To those I have offended, I apologise and ask forgiveness.

"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."

Last Monday it was announced that Cardinal O'Brien would resign his post with immediate effect.

The move came a day after a newspaper reported that three priests and a former priest had complained about him to the Vatican over alleged "inappropriate" behaviour stretching back 30 years.

His resignation was accepted by the Pope on February 18. The cardinal, who initially said he was taking legal advice when the allegations against him emerged, had been due to retire later this month when he turned 75.

In an earlier statement issued via the Catholic Church's media office in Scotland, the cardinal said: "For any failures, I apologise to all whom I have offended."

Cardinal O'Brien, who recently advocated priests marrying, has been an outspoken opponent of plans to legalise same-sex marriage.

Last year his stance earned him the Bigot of the Year award from gay rights group Stonewall.