'When I was still a simple priest and for a while when I began as a bishop, I sexually abused a young man in my close entourage,' the Bishop of Bruges, Roger Vangheluwe, said in a statement released by the Vatican.
In the statement, Roger Vangheluwe asked for forgiveness for his offences.
The latest blow to the Catholic Church comes after a victim of a US paedophile priest announced he is taking legal action against the Pope and the Vatican.
The man, whose identity has not been revealed, was a victim of Fr Lawrence C Murphy, who is thought to have abused up to 200 pupils at a school for deaf pupils in Milwaukee, Wisconsin.
Fr Murphy was moved from the school in 1974, but was never prosecuted or defrocked before he died in 1998.
The victim's lawyer, Jeff Anderson, said he wanted the Pope and the Vatican to release all confidential files on child abuse.
'There is a painful and long history of the Vatican and the top officials... muffling and suppressing the truth and protecting themselves and their own reputation instead of protecting the children,' Mr Anderson said at a press conference.
'This suit demands further action by the Vatican and the removal of every single priest that has offended a single child and every single bishop and cardinal that has been complicit in those crimes.'
Mr Anderson, who has spent decades pursuing justice for victims of child sex abuse, said the case is far broader than a suit he brought against the Vatican in 2002 and is 'unprecedented' in its scope and demands.