The man, he said, told him that he had been sexually assaulted by a priest at another parish. Samson added that the man refused to name his aggressor or the church.

Samson, 59, who served as a military chaplain during the Persian Gulf War and teaches counselling at the University of Ottawa, said over the years he had listened to many young people in crisis. But he said he never saw one in such "intense psychological distress."

He said he advised the man to seek professional counselling.

Deeply troubled, Samson thought it was important he recount the story to his colleagues.

"I shared my suffering and my anger toward that priest who had ruined the life of a young person of 18 years old," he said.

But he said his story was quickly interrupted.

He was cut off within two or three minutes, while discussing the issue with three other priests over lunch at the refectory in June.

"The community superior became enraged," Samson said.

"He said, 'Don't talk about this here. It can't be. We don't talk about this here.' "

Later that day, he alleges that same community superior, Claudel Petit-Homme, barred him from eating lunch in the dining hall.

At the time, Samson considered quitting, but said he was encouraged by a colleague to stay on at the oratory where he had worked part-time since last year.

The oratory declined a request by The Canadian Press to interview Petit-Homme.

Last month, Samson said he unsuccessfully asked another superior to help him overturn his refectory expulsion.

Then, on Sunday, he said he was fired for reasons that he described as relatively minor offences, such as failing to do up his collar all the way.

The other reasons included Samon's refusal to put the Host wafer on worshippers' tongues during flu season (a stance he took because he has a heart condition) and because he had made mistakes in the wording of absolution during confession.

He said his superior denied that his firing had anything to do with him rehashing the sexual-assault allegation over lunch.

The oratory's administration refused to comment on Samson's allegations, saying the reasons for his removal are confidential. Spokeswoman Danielle Decelles told Quebec City's Le Soleil earlier this week that he was let go due to worshippers' complaints.

But Samson insists he was well-liked by parishioners and believes he was fired for raising a taboo subject.

"I find this difficult because as priests we give our lives to the church," said Samson, as his voice cracking with emotion.

"And it's sad how we can be betrayed by this church."

St. Joseph's Oratory, a towering house of worship perched on the slope of Mont Royal, attracts two million pilgrims and visitors each year from around the world.

The impressive building was founded in 1904 by Saint Andre, a humble Quebec cleric then known as Brother Andre. He was credited with miracle healings before his death in 1937, and was canonized three years ago.

Samson's allegations surface as the Vatican tries to clean up its global image on the issue.

Pope Francis has instructed the head of the Vatican office that handles abuse cases to act "decisively" to protect children, to help victims and to punish priests guilty of sexual crimes.

In July, Pope Francis introduced new legislation to cover clergy and staff who live and work in Vatican City.

The law defines crimes of sexual violence, and has increased punishments to range from five to 10 years in prison. Aggravating circumstances bring the maximum sentence up to 12 years and a fine of 150,000 euros.

Back in Montreal, Samson believes he was well-positioned to speak out.

He earns a $139,000 salary as a full-time university professor, and his reasons for wanting to be a priest are not strictly a question of livelihood.

"I told myself that if I don't talk, who will? No one can really talk because they are too vulnerable."

- with files from Associated Press

By Andy Blatchford, The Canadian Press