Lawyers for a man who was sexually abused decades ago by a priest at a school for the deaf in the US state of Wisconsin have withdrawn their lawsuit naming Pope Benedict XVI and other top Vatican officials as defendants.

It is a major victory for the Holy See, which has long insisted the pope bears no liability for the actions of an abusive priest.

Lawyer Jeff Anderson had filed the lawsuit with great fanfare at the peak of a European explosion of the sex abuse scandal in 2010.

He alleged that the former Cardinal Joseph Ratzinger and his deputies knew about allegations of sexual abuse at St John's School for the Deaf and prevented internal punishment of the accused priest.

The lawsuit had helped shift the blame for priestly sex abuse in the public mind away from bishops - who are responsible for their priests - to the Vatican and Benedict himself.

The Vatican at the time had rejected Mr Anderson's lawsuit as a publicity stunt, and the Vatican's US lawyer said the dismissal demonstrates that the case was meritless and never should have been filed in the first place.

Mr Anderson's firm filed a voluntary motion in US District Court in Milwaukee to dismiss the lawsuit.

Mr Anderson said: "There really is no compelling reason to move forward with this battle on two fronts when we're making ground on one."

Jeffrey Lena, a Vatican lawyer, said Mr Anderson had settled on a convenient excuse for dismissing the lawsuit.

"The real reason is, he was required to file a response to our motion to dismiss, and he knew he was going to lose the suit," Mr Lena said.