The Louisiana Supreme Court has ordered a priest to break the seal of confession, a move his diocese called an “assault” on the Catholic faith.

The court ordered Fr Jeff Bayhi, of Baton Rouge diocese in Louisiana, to tell a hearing whether he advised a young girl during confession to keep quiet about an incident of sexual abuse she said she had suffered.

The ruling by the Louisiana Supreme Court that overturned a lower court’s decision and ordered a hearing on a lawsuit brought by parents of a girl who was allegedly molested by an adult man.

The lawsuit compels Fr Bayhi, who is bound by canon law not to reveal what the girl confessed or what he said to her, to testify whether or not there were confessions "and, if so, what the contents of any such confessions were."

Both the girl and her alleged abuser were members of Fr Bayhi’s church in the town of Clinton.

The petition alleged that on three occasions in 2008 the girl, who was then 12, told Fr Bayhi that a church member had inappropriately touched her, kissed her and told her "he wanted to make love to her."

The child testified during deposition that Fr Bayhi's advice to her was to handle the issue herself because "too many people would be hurt". Court documents also say that she testified, "He just said, this is your problem. Sweep it under the floor."

The girl’s parents claim that the Fr Bayhi was negligent and that the abuse continued after the girl made her confession.

The alleged abuser died in 2009 while undergoing a criminal investigation.

The diocese, which has also been named as a defendant in the lawsuit against the girl’s alleged abuser, vigorously opposed the Supreme Court decision.

In a two-page statement released on Monday it said the Church had “great compassion” for those who have “indicated an experience of such egregious misconduct”.

But it added: “[The court’s decision] assaults the heart of a fundamental doctrine of the Catholic faith,” it said. “For a civil court to inquire as to whether or not a factual situation establishes the Sacrament of Confession is a clear and unfettered violation of the Establishment Clause of the Constitution of the United States.”