Brasília, Brazil (AFP) — The families of a British journalist and Brazilian indigenous expert who went missing deep in the Amazon after receiving threats made distraught pleas Tuesday to authorities in Brazil to accelerate the search operation.

Veteran freelance journalist Dom Phillips, 57, and respected indigenous specialist Bruno Pereira, 41, went missing early Sunday while travelling by boat in the remote Javari Valley near Brazil’s border with Peru, where Phillips was researching a book.

As the 48-hour mark passed, speculation swirled on where the men were and whether there could have been an accident or foul play.

“I want to make an appeal to the government to intensify the search,” Phillips’s Brazilian wife, Alessandra Sampaio, said in an emotional video message.

“We still have some small hope of finding them. Even if I don’t find the love of my life alive, please find them,” she said, choking back tears.

The Brazilian Government expressed its “grave concern,” and said police were taking “all possible measures to find [the men] as quickly as possible.”

But the authorities faced accusations of failing to act urgently enough.

Despite the Government’s pledge to deploy the army, navy and federal police for the search, three indigenous rights groups in the region said in a joint statement that just six state police officers were actively working on the operation, and urged the Government to deploy helicopters and a task force.

President Jair Bolsonaro, meanwhile, drew criticism for appearing to blame the missing men, both of whom have extensive experience in the Amazon rainforest basin.

“Two people in a boat in a region like that, completely wild — it’s an unadvisable adventure. Anything can happen,” Bolsonaro said.

“Maybe there was an accident, maybe they were executed.”

The far-right president has faced accusations of fuelling invasions of indigenous lands in the Amazon with his pro-mining and pro-agribusiness policies.

Pereira, an expert currently on leave from Brazil’s indigenous affairs agency, FUNAI, who knows the region well, has spent much of his career fighting such invasions.

He has regularly received threats from poachers, loggers and miners trying to invade isolated indigenous groups’ land.

He and Phillips had received another threat just last week, according to indigenous rights groups.

The Government said investigators were not ruling out “criminal activity” in the disappearance.

Officers brought two people in for questioning Monday, believed to be among the last to have been in contact with the missing men, police said in a statement.

Neither was detained, it said.

As two days passed since the two men’s disappearance with no news, their families urged the authorities to act quickly.

“Time is a key factor in rescue operations, particularly if they are injured,” Pereira’s family said in a statement.

It said his partner, three children and other relatives were in “anguish.”

Phillips’s sister Sian posted a video message online, fighting back tears.

“We are really worried about him and urge the authorities in Brazil to do all they can,” she said. “Every minute counts.”

Phillips, who is based in the northeastern city of Salvador, had previously accompanied Pereira in 2018 to the Javari Valley for a story in The Guardian.

The 85,000-square-kilometre (33,000-square-mile) reservation is home to around 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.

The region has seen a surge of illegal logging, gold mining and poaching in recent years, and its remoteness makes it a haven for drug traffickers, said Fiona Watson, research director at indigenous rights group Survival International.

“You’re talking about dense tropical forest,” she told AFP.

“The operation to try and locate Bruno and Dom is immensely challenging.”