The Vatican has confirmed the authenticity of a letter in which a cardinal praised a French bishop for not denouncing a paedophile priest.
The letter, originally published in the French press, was written in 2001 by Cardinal Dario Castrillon Hoyos, then in charge of clergy around the world.
A Vatican spokesman said the letter showed the wisdom of a 2001 decision to centralise the handling of abuse cases.
The case comes amid a continuing child sex abuse scandal engulfing the Church.
Allegations of abuse and cover-ups have emerged recently from countries across Europe as well as the US.
The letter from Cardinal Hoyos was addressed to the bishop of Bayeux-Lisieux in northern France, Pierre Pican.
Father Pican had just been given a three-month suspended prison sentence for not denouncing Rene Bissey, an abbott who was sentenced to 18 years in prison in 2000 for paedophilia.
"I congratulate you on not having spoken out to civil authorities against a priest," wrote Cardinal Dario Castrillon Hoyos, who at the time was prefect of the Congregation for the Clergy.
"You have done well and I am delighted to have an associate in the episcopate who... preferred prison to speaking out against a son-priest."
Vatican spokesman Father Federico Lombardi said the letter confirmed "how opportune it was to centralise treatment of cases of sexual abuse of minors by clerics under the Congregation for the Doctrine of the Faith."
That step was taken in 2001 by Cardinal Joseph Ratzinger - now Pope Benedict XVI - who headed the Congregation for the Doctrine of the Faith at the time.
Earlier this week, the Vatican published what it said was a long-standing Church policy telling bishops that they should report abuse cases to police - though critics said the move was an attempt to rewrite history.
On Thursday, Pope Benedict called on Roman Catholics to "do penance" for their sins, an apparent reference to the recent sexual abuse scandal.