A British journalist and a Brazilian indigenous expert have gone missing in the Amazon rainforest, authorities and rights groups said on Monday.
Veteran foreign correspondent Dom Phillips, 57, went missing while researching a book in the Brazilian Amazon's Javari Valley with respected indigenous expert Bruno Pereira, The Guardian reported.
Mr Phillips has been a longtime contributor at the newspaper.
The pair had travelled by boat to Jaburu lake, in the northern state of Amazonas near Brazil's border with Peru.
They were expected to return to the city of Atalaia do Norte on Sunday morning, said the Univaja and OPI rights groups.
The men had "received threats in the field" last week, said the groups. Mr Pereira, an expert at Brazil's indigenous affairs agency Funai, has regularly received threats from loggers and miners trying to invade isolated indigenous groups' land.
Funai told AFP it was collaborating with local authorities on the search effort. It said Mr Pereira was on leave from the agency "to pursue personal interests."
Mr Phillips and Mr Pereira had travelled to the region around a Funai monitoring base, and reached Jaburu lake Friday evening, Univaja and OPI said.
They started the return trip early on Sunday, stopping in the community of Sao Rafael, where Mr Pereira had scheduled a meeting with a local leader to discuss indigenous patrols to fight the "intense invasions" that have been taking place on their lands, the groups said.
When the community leader did not arrive, the men decided to continue to Atalaia do Norte, about a two-hour trip, they said.
They were last sighted shortly after near the community of Sao Gabriel, downstream from Sao Rafael.
The pair were travelling in a new boat with 70 litres of petrol — "sufficient for the trip" — and were using satellite communications equipment, the groups said.
The federal prosecutors' office said it had sent police to investigate and activated a search operation, to be led by the Brazilian navy.
Two initial searches by indigenous locals "with extremely good knowledge of the region" have found no trace of the men, said Univaja and OPI.
Two fisherman arrested
According to the newspaper O Globo, two fishermen were arrested by the police on Monday night, including a person with whom the two men had an appointment.
The missing men's families voiced alarm, along with high-profile organisations and figures including Brazilian ex-president Luiz Inacio Lula da Silva.
"We implore the Brazilian authorities to send the national guard, federal police and all the powers at their disposal to find our cherished Dom," Mr Phillips's sister's partner, Paul Sherwood, wrote on Twitter.
"He loves Brazil and has committed his career to coverage of the Amazon rainforest. We understand that time is of the essence."
The Guardian said it was "very concerned" about Mr Phillips, whose work has also appeared in The New York Times, The Washington Post and other leading media.
"We condemn all attacks and violence against journalists and media workers. We are hopeful that Dom and those he was travelling with are safe and will be found soon," it said.
Mr Phillips, who is married and lives in the north-eastern city of Salvador, had previously accompanied Pereira in 2018 to the Javari Valley for a story in The Guardian.
The 85,000 square kilometre reservation is home to about 6,300 indigenous people from 26 groups, including a large number with virtually no contact with the outside world.
Funai's base there, set up to protect indigenous inhabitants, has come under attack several times in recent years. In 2019, a Funai officer there was shot dead.