A British journalist has disappeared in one of the most remote corners of the Amazon a few days after his guide received threats, according to reports.
Dom Phillips, a contributor to The Guardian in Brazil, disappeared with a local expert.
The couple was last seen over the weekend in the Javari region of the state of Amazonas, near the border with Peru.
According to The Guardian, the journalist was traveling with Bruno Araujo Pereira, a former government official whose mission was to protect uncontacted tribes in Brazil.
The newspaper said Pereira had received several threats from loggers and miners in the region.
On Monday, local indigenous leaders sounded the alarm after the couple disappeared during an information mission on the river network around the city of Atalaia do Norte, the entry point to the Javari reserve.
The Univaja indigenous group said the men had sailed last week to a region known as Lago do Jaburu.
They arrived on Friday and reportedly began their journey back to Atalaia do Norte on Sunday morning.
The river trip should not have taken more than a few hours, and a research group was sent around 2pm after they could not arrive.
Local police and the army are believed to be involved in the search.
A Guardian News & Media spokesman said: “The Guardian is very concerned and is urgently seeking information on Mr Phillips’ whereabouts and condition.
“We are in contact with the British embassy in Brazil and local and national authorities to try to establish the facts as soon as possible.”
Phillips has reported on Brazil for more than 15 years for newspapers such as The Guardian, the Washington Post, the New York Times and the Financial Times.