Brazil’s military is searching for missing British journalist Dom Phillips as police said they have arrested one person in connection with his disappearance.
The army and navy joined the search for Mr Phillips and Bruno Pereira, an indigenous expert, who went missing in a region containing a vast indigenous reserve that is larger than Austria.
One suspect has been arrested, police said, and four fishermen questioned as witnesses. The fishermen are known to have clashed with authorities earlier over fishing rights.
Mr Phillips, a freelance journalist, and Mr Pereira, a former senior official with federal indigenous agency Funai, were last seen on Sunday.
Indigenous leaders have helped with the search in the Amazon rainforest’s Vale do Javari area and talked to local people.
One of them, Binan Tuku, said: “I asked where Bruno is, they said Bruno had left, then I took two litres of gasoline, and I came through the same way they should have passed, and didn’t find anything. I arrived here in Atalaia at 4 or 5pm, and I was told Bruno was not there, that he had disappeared.”
Gilson Mayuruna, a Vale do Javari indigenous leader, added: “Today, the indigenous movement is in search for clues on the disappearance of Bruno Pereira and Dom Phillips, who was accompanying him to film and show the problems of Javari people.”
They had been on a reporting trip in the Javari Valley, a remote jungle area that is home to the world's largest number of uncontracted indigenous people, as well as cocaine-smuggling gangs, illegal hunters and fishermen.
Amazonas state police said they had interviewed “four people as witnesses and another as a suspect”.
Both men's families urged the authorities to act fast and a group of friends and journalists appealed to Brazil’s authorities for help. Mr Phillips's sister Sian posted a video message online, fighting back tears.
Mr Pereira's family said: “We are really worried about him and urge the authorities in Brazil to do all they can. Every minute counts.”
“Time is a key factor in rescue operations, particularly if they are injured,” they added.
The pair were returning by boat to the city of Atalaia do Norte, about an hour’s trip, but failed to get there.
Mr Pereira is one of the Funai agency’s most experienced employees operating in the Vale do Javari area.
He oversaw the agency’s regional office and the co-ordination of isolated Indigenous groups before going on leave. He has received a stream of threats from illegal fishermen and poachers, and usually carried a gun.
Mr Phillips, 57, has reported from Brazil for more than a decade and was working on a book about the preservation of the Amazon with support from the Alicia Patterson Foundation, which gave him a year-long fellowship for environmental reporting.
The place where they went missing is the primary access route to the Vale do Javari, Brazil’s second-largest indigenous territory, which is bigger than the US state of Maine.
Local people have said it is highly unlikely the men would have got lost in that area.