STV News in Glasgow said the cardinal initially had chosen to contest "anonymous and non-specific" claims against him made public last week regarding sexual misconduct with four priests.
The cardinal, however, said Sunday, "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 complaints allege inappropriate behavior dating back as far as 1980, The Observer said. A former priest said he was a 20-year-old seminarian at St. Andrew's College where O'Brien, his "spiritual director," approached him inappropriately after night prayers. Another priest said O'Brien initiated inappropriate contact during a visit to his parish. A third priest said he experienced unwanted behavior after a late-night drinking session when visiting O'Brien at the archbishop's residence, and the fourth priest says O'Brien used night prayers as an excuse for inappropriate contact, The Independent of London reported last week.
"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. I will play no further part in the public life of the Catholic Church in Scotland," he said.
O'Brien appears to be out of the country, and he will not participate in the conclave to elect the new pope.