The unprecedented and historic case involves an Irish priest transferred to the US after being accused of molesting young boys in Ireland.

This is the first time a court in the US has ruled the Vatican can be sued for offences committed by priests.

A man in Portland, Oregon, launched the legal action against the Vatican, claiming it was liable as senior clergy there controlled the movements of priests in the US.

The alleged victim, named only as John Doe, claimed he was abused in the 1960s when he was just 15 or 16.

Pope Benedict may be asked to give a statement ahead of any civil trial, said the man’s lawyer, Jeff Anderson.

Fr Andrew Ronan, who died in 1992, allegedly admitted abusing boys in Ireland and then in Chicago before being transferred to Portland.

The ruling, which is likely to be appealed by the Vatican to the US Supreme Court, paves the way for thousands of other alleged victims to sue the Holy See and the Vatican.

The Vatican and its lawyers, who have vigorously opposed the action first brought seven years ago, claimed it had immunity from such actions due to its status as a foreign state.

Under the Foreign Sovereign Immunities Act, a foreign state cannot be sued in the US except under exceptional circumstances.

Mr Anderson went on to suggest that the three judges in Portland ruled John Doe met the exception because the Vatican had "control over the priest in terms of his removal and his transfers".

He said: "The Church has enough control that it can be held legally responsible as the master of the priest.

Reflecting on the possible repercussions of the finding Mr Anderson suggested the ruling "opened the door to survivors to sue the Vatican for its role in the cover-up of priests and molestations by them".

Mr Anderson also described the ruling as a major and historic breakthrough.

Fr Ronan is alleged to have abused boys in Ireland before being transferred to Chicago, where he was accused of molesting three more children.

The Irish priest was then moved to Portland.