A 26-year-old Briton has been killed by a 29-year-old Canadian man in the Peruvian Amazon on Wednesday night in self-defence after he was attacked by the Briton who was under the influence of a hallucinogenic plant brew. Both the men took the brew known as ayahuasca at a spiritual retreat, authorities say.

Normando Marques, a police chief in the region, said that people saw the British man, Unais Gomes, attacked Canadian Joshua Andrew Freeman Stevens with a knife at the ayahuasca ceremony near the village of Iquitos.

Ayahuasca is made by brewing an Amazonian vine and plants containing dimethyltryptamine (DMT), which gives psychedelic experiences but is rarely associated with violence.

"It might be folkloric, spiritual or whatever else, but that doesn't mean it isn't a drug that dramatically alters your state of mind," the Daily Telegraph quoted Marques as saying.

According to a witness, who wished to remain anonymous, Gomes took a kitchen knife from the alternative health centre Phoenix Ayahuasca to stab Stevens. However, scStevens ended up stabbing him in the chest and back with the same knife. The health centre, however, did not respond to any request for comments.

Gomes was rushed to hospital after the incident but could not be saved. Stevens was taken into police custody on Thursday.

The traditional indigenous brew has received a lot of popularity in recent years with multiple jungle retreats offering the experience to tourists under the supervision of a guide or shaman. Ayahuasca is believed to help ease depression and other health issues.

The Facebook page of Phoenix Ayahuasca from where the knife was seized by Gomes has described it as a safe place to try plant medicines.

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