The Quebec Court of Appeal has authorized a new class action lawsuit against a major Catholic organization for alleged sexual abuse committed by some of its members.

The Congregation of Holy Cross, which runs St. Joseph's Oratory, has already apologized and paid out compensation, but more victims have come forward.

The main complainant in the case was a student at the Notre Dame des Neiges Catholic elementary school between 1951 and 1955.

He alleges that twice a week, for years, one of the Catholic brothers perfect a sex act on him at the school.

Lawyer Gilles Gareau said the complainant accused another person of molesting him at the Oratory.

"He was approximately between nine and 12 years old during the time when the assaults took place," said Gareau.

Sixty years later the man still has flashbacks and feels sick whenever he sees the Oratory.

The Oratory issued a statement in response to the claim.

"The request refers to an incident that took place more than 60 years ago. A single cleric was involved and this person is now deceased."

The organization said that in the wake of multiple cases of sexual assault it has completely revamped policies to ensure sexual assault can no longer happen.

"[We] vigorously condemn all inappropriate acts that may affect minors and adults and that a strict policy of zero tolerance is applied at all times.

Gareau said there could be up to 500 more victims who were assaulted between the 1940s and 1980s.

Holy Cross ran dozens of orphanages, schools, and colleges, with Gareau saying abuse was known, and covered up.

"The same brother assaulted a number of children by being moved from one institution to the next. I call it the pedophile musical chair," said Gareau. "When things got too hot, they moved them. It didn't resolve the problem but they moved them."

Because each victim is seeking between $50,000 and $150,000 in moral and punitive damages, the case could be worth as much as $75 million.

Sebastien Richard, a spokesman for a victims' rights group, said the landmark $18 million settlement reached in 2013 prompted about 40 new alleged victims to come forward.

Many of the victims are elderly.

"The problem to me is to be able to reach to them and that they will be willing to go through this process and they will seek to get back their dignity and they will be able to confront their aggressor so they will be able to rest in peace once their life is ended," said Richard

Richard said the current class-action names more institutions.

"The Holy Cross Congregation cannot be exempted of all the responsibilities for all these abuses they have been committing for tens and tens of years. They have to pay for that. They have to be pointed at for doing these abuses and not having any kind of interest in their victims. Their victims were, for them, just toys," said Richard.