A senior American priest warned the Vatican 47 years ago that there were problems with pedophile priests in the U.S.

The Rev Gerald Fitzgerald sent a letter to Pope Paul VI in 1963 outlining his concerns over the "problem of the problem priest."

The letter is damning evidence that the Vatican was fully aware – or should have been – of the sexual abuse which spiraled out of control within the American Church.

Fitzgerald strongly recommended that such pedophile priests be defrocked rather than shuttled from parish to parish, as was the practice in Ireland and the U.S.

Fitzgerald, who founded the Servants of the Paraclete, was so convinced that the priests would be repeat offenders that he even tried to buy an island to isolate them from the general public.

Fitzgerald discussed the issue with both the Pope and several American bishops.

"Personally, I am not sanguine of the return of priests to active duty, who have been addicted to abnormal practices, especially sins with the young," Fitzgerald wrote. "Where there is indication of incorrigibility, because of the tremendous scandal given, I would most earnestly recommend total laicisation. I say 'total'... because when these men are taken before civil authority, the non-Catholic world definitely blames the discipline of celibacy for the perversion of these men."

 Fitzgerald was not just sending the letter in the hope that it might be read.

He had been asked to write the letter by none other than Pope Paul VI who met with Fitzgerald in the U.S. to talk about cases of abuse in the US.

The letter has been discovered by lawyers acting for victims of alleged sexual abuse in Los Angeles.

"The letter proves Vatican officials knew about clergy abuse decades ago and should have done more to protect children," said lawyer Anthony DeMarco.

But Church officials in Los Angeles are claiming it was unlikely that Pope Paul VI ever saw the  letter - even though the Pope had commissioned it.

Warning: The Reverend Gerald Fitzgerald who warned the Vatican in 1963 that pedophile priests should not be allowed to resume duties