Criminal probe in Brazil's UK journo hunt

Brazilian police have opened a criminal probe and interviewed at least four witnesses believed to be among the last to have seen a British journalist and an indigenous expert who have gone missing in a remote and lawless part of the Amazon jungle.

Guilherme Torres, the head of the interior department of Amazonas state's civil police, told Reuters a criminal investigation had been opened and four witnesses interviewed as the search goes on to locate the journalist, freelancer Dom Phillips, and his companion Bruno Pereira, a former senior official with federal indigenous agency Funai.

Torres said Pereira had recently received a threatening letter from a local fisherman who police were trying to locate.

He said his colleagues had interviewed two fishermen as witnesses on Monday, with two more quizzed on Tuesday.

"We are indeed working with the hypothesis that a crime might have occurred, but there is another, much larger possibility, that they're lost," Torres said.

"Now, our priority is to find them alive, especially in these first hours. In parallel, a criminal probe has been opened to see if there was some crime committed."

Brazil's navy and army dispatched search teams in boats and helicopters to the area, with support from federal and state police.

Pereira and Phillips, who has written for The Guardian, The Washington Post and others, went missing on Sunday during a reporting trip in the Javari Valley.

The Union of Indigenous Peoples of the Javari Valley (UNIVAJA), which first announced the pair's disappearance, criticised Brazil's security forces for taking so long to deploy search teams.

The navy sent a launch up river on Tuesday but they arrived after dark. The army dispatched troops on Tuesday, sending dozens of soldiers in river boats to patrol the streets of nearby villages.

The vast region, which borders Peru and is home to the world's largest number of uncontacted indigenous people, is threatened by illegal miners, loggers, hunters and coca-growing gangs who make the raw material for cocaine.

Torres said he could not rule out that their disappearance was linked to the gangs operating in the lawless region.

UNIVAJA representatives said Pereira and Phillips were with an indigenous patrol that was threatened by armed men on Saturday. The pair recorded the confrontation on a mobile phone.

The disappearance of the two men, who both had years of experience working in the complex and inhospitable Amazon rainforest, sparked global concern from human rights groups, environmentalists, politicians and press freedom advocates.

In an emotional TV interview, Phillips' wife, Alessandra Sampaio, urged authorities to intensify their search efforts, "because we still have a little hope of finding them".

Pereira's family issued a statement calling for a robust search operation, adding "we are also very hopeful that there was an accident with the boat and that they are waiting for help".

President Jair Bolsonaro, who has faced tough questioning from Phillips at news conferences about policies that have weakened environmental law enforcement, said in a TV interview on Tuesday the two men "were on an adventure that is not recommended".

"It could be an accident, it could be that they were executed, anything could have happened," he said.