The Canadian man who killed a British tourist in Peru says he was forced to do it to protect his own life and the lives of two others.

Joshua Andrew Freeman Stevens says he killed Unais Gomes in December, after Gomes tried to stab him at a ceremony involving hallucinogens.

"I really thought I was going to die," Stevens, 29, told CTV Winnipeg on Tuesday. He added that Gomes, a 25-year-old British tourist, had been a friend of his, and he deeply regrets what happened.

Stevens was allowed to return to his home in Winnipeg after the incident last month, at a rainforest retreat called Phoenix Ayahuasca, near the town of Iquitos in Peru.

Stevens said Gomes had taken a double dose of a hallucinogenic drink called ayahuasca, after which he became unstable.

"I could hear him screaming the name Yahweh, and I was very concerned because he was screaming it, just screaming it at the top of his lungs," Stevens said, recalling the incident.

He says he approached Gomes to see if he was alright, at which point Gomes started shouting: "You are Yahweh, you are Yahweh, and it's time to get your demons out, brother. It's time to get your demons out."

Then, Stevens says Gomes attacked. So, Stevens said, he ran to the kitchen of the retreat to find help, but Gomes followed him and tried to attack him with a kitchen knife. Stevens said he used a steel pot to defend himself.

"He swiped at me and he hit the table, and his knife broke, and I went to hit him with the pot, and I hit him in the side of the body and my pot broke," he said.

Gomes dropped the first knife and went for a butcher's knife, so Stevens tried to wrestle it away from him. Two staffers from the retreat then joined the fight, and Stevens was able to get the knife away from Gomes in the struggle. However, Gomes soon began attacking the workers, and Stevens feared he would kill them, he said.

"What I said to myself was if he gets this knife back, he's either going to kill me or the other two men here," Stevens said. "And that's when I made the decision to stab him."

Stevens said he stabbed Gomes twice, killing him.

Peruvian police arrested Stevens after the incident, and held him for 24 hours before releasing him. Police reportedly ruled the killing an act of self-defence.

Stevens was later allowed to return home to Winnipeg, although he may be summoned back to Peru if the case goes to trial, he said.

The Canadian man says he and Gomes were good friends.

"He said we were going to be lifelong friends, him and I," Stevens said, while choking back tears.

The owners of Phoenix Ayahuasca describe it as a "shamanic healing retreat" on their website.

In a statement posted online, owner Tracie Thornberry said she could not say much about the killing until the police investigation is complete.

"We are deeply shocked and saddened by what happened at our center," Thornberry wrote. "Our thoughts and prayers are with the two boys, Unais and Joshua, and with their families.

"I have full faith in our staff to act appropriately even in difficult situations. Unfortunately their physical intervention could not prevent this tragedy."

The hallucinogenic brew called ayahuasca, or yage, has been used for centuries by indigenous tribes in South America for its alleged healing properties. It has also become popular among Western tourists for the mind-altering experiences it can provide.

Stevens said he went to the retreat in search of a cure for a skin condition.