Authorities in Peru have launched an investigation after the body of a 71-year-old Briton, who was a Catholic missionary and environmental activist, was found in the Amazon city of Iquitos.

Students found the body of Paul McAuley on Tuesday in a hostel that he founded for indigenous students in the poor Belén neighbourhood. Local media reported he had been burned.

Officials from the state prosecutor’s office are questioning six indigenous males who lived in the hostel, run by McAuley.

Born in Portsmouth, McAuley was a lay Catholic brother with the De La Salle teaching order. He came to the world’s attention in 2010 when Peru ordered his expulsion for helping Amazon tribes to fight against the onslaught of oil and gas companies invading the rainforest. At the time, local media labelled him as a “Tarzan activist”, “white terrorist” and “incendiary gringo priest”.

Facebook Twitter Pinterest Paul McAuley. Photograph: Universal News And Sport (Europe)

McAuley eventually beat the expulsion order through the courts. He had gone to the Peruvian Amazon in 2000 to help indigenous activists and set up a civil association, Red Ambiental Loretana.

When the Guardian visited McAuley in 2010, shortly before the government tried to expel him, he said he felt at home in the region and that his Catholicism had fused with elements of an Amazonian spiritual belief based on the concept of energy. “More than its oil, what the west needs is the Amazon’s spiritual energy,” he said.

Slightly built, bespectacled and balding, he did not resemble Tarzan, but his mild manner belied outspoken political activism. He took pride in his reputation as a “troublemaker”, seeing it as a badge of social justice. In a voice at times so soft you had to lean forward to hear, he denounced oil companies and Peru’s government and security forces as vandals and oppressors. He believed they were contaminating the Amazon’s culture and environment, imperilling uncontacted tribes, and needed to be resisted.

McAuley saw his vocation as educating and helping to mobilise marginalised indigenous groups. When not visiting remote villages by boat he spent his days in Iquitos teaching, battling patchy internet facilities and riding around town on a scooter.

Perched by the Amazon river and inaccessible by road, Iquitos attracts oil firms, backpackers, missionaries, traders and sex workers.

A few years after arriving in Peru in 1995, McAuley was awarded an MBE for his work in setting up a school in the poor Punta Piedra shanty in the capital, Lima. Had he not already given the award away, he said in 2010, he would have sent it back to the Queen in protest against British companies’ presence in the rainforest.

Facebook Twitter Pinterest Oil pipelines in the Amazonian region of Loreto, near Iquitos, August 2011. Photograph: Reuters

Peru’s Episcopal Conference paid tribute to McAuley and called on the authorities to thoroughly investigate the crime.

“It’s a big loss,” Robert Guimaraes, the president of the indigenous federation Feconau, told the national radio broadcaster RPP.

“His tireless work to protect the environment, his great concern for the rights of the Amazon indigenous people … How could such an honourable man meet his end in this way?”

Julia Urrunaga, the Environmental Investigation Agency’s Peru director, tweeted: “It was fascinating to be around hermano Paul McAuley and see the positive impact that he had on the young indigenous leaders around him, supporting and inspiring a peaceful fight for their rights and their forests.”

The Foreign Office said: “We are in contact with the authorities in Iquitos following reports of the death of a British man in the Peruvian jungle.”

In an upbeat Christmas message to friends and supporters in 2011, McAuley expressed relief that the expulsion order had been reversed and took pride in the decision of secondary school students to name their graduation group after him. “They usually take the names of historical figures (now dead) so let’s hope its not a prophetic announcement!” he wrote.

