By Damien Gayle | DailyMail.co.uk

A priest joked about how hard it was to have sex with three boys in one week, claimed internal Catholic church documents revealed in court for the first time yesterday.

The startling testimony came in the trial of Monsignor William Lynn, 61, who is accused of helping the Philadelphia archdiocese bury priest abuse complaints in secret files.

Lynn, who faces charges of child endangerment and conspiracy, is the first Roman Catholic church official to be charged in the U.S. for his handling of priest abuse complaints.

The scandal of child sex abuse by Catholic priests has reverberated internationally, and caused a worldwide crisis of faith in the Roman church.

Prosecutors are detailing allegations made against nearly two dozen priests since 1948 to show Lynn and other officials kept suspected predators in jobs around children.

Giving evidence, a detective read internal church memos about a priest who is said to have ’joked about how hard it was to have sex with three boys in one week.’

The priest’s accuser also alleged that the priest had a ’rotation process’ of boys spending time sleeping with him.

Jurors also heard testimony telling of a 1992 complaint about a priest accused of molesting boys at a church-owned camp three decades earlier.

Several junior counselors complained in the early Sixties that the priest was on the prowl at night, molesting them in their tents.

They said it was a well-known secret among teenage counselors for several years.

The priest remained in ministry, working at three archdiocesan high schools and serving as assistant superintendent of Catholic schools through 2004.

Confronted after a man complained to the archdiocese in 1992, he admitted the ’sin’ of masturbation and said he had read up on that subject because so many people were mentioning it in the confessional.

Lynn is mobbed by reporters as he leaves court in Philadelphia: His defence claims that his efforts to address the problem were blocked by senior churchmen.