The letter, sent from the Catholic authority in Rome to Irish bishops, states that it would be "highly embarrassing" should the cases of pedophilia reach the public.

The letter is the "smoking gun we've been looking for," in the case for Vatican complicity in child abuse cases, according to Joelle Casteix, director of the Survivors Network of Those Abused by Priests.

"The letter is of huge international significance, because it shows that the Vatican's intention is to prevent reporting of abuse to criminal authorities. And if that instruction applied here, it applied everywhere," according to Colm O'Gorman, director of the Irish chapter of Amnesty International.

A copy of the letter can be accessed on the Associated Press website.