A British journalist and an Indigenous affairs expert are missing in a remote part of Brazil’s Amazon region, a local Indigenous association said on Monday.

The area has been marked by violent conflicts between fishermen, poachers and government agents.

Dom Phillips, a regular contributor to the Guardian newspaper, and Bruno Araujo Pereira were last seen at 7am on Sunday in the Sao Rafael community, according to the Unijava association for which Mr Pereira has been an adviser.

They were returning by boat from the Vale do Javari indigenous land and were bound for the city of Atalaia do Norte, about an hour away, but never showed up.

Mr Pereira, who has received several threats in the region, is currently on leave from his post with Brazil’s indigenous affairs agency. Mr Phillips also has contributed to the Washington Post and New York Times.

The Guardian quoted a spokesman as saying it “is very concerned and is urgently seeking information about 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”.

The region has seen repeated shootings between hunters and fishermen and official security agents, who have a permanent base in the area, known for having the world’s largest population of uncontacted indigenous people.

Brazil’s federal public prosecutors said they have opened an investigation and mobilised the federal police, Amazonas state’s civil police, the national guard and navy.

The Vale do Javari is also a major route for cocaine produced on the Peruvian side of the border, then smuggled into Brazil to supply local cities or be shipped to Europe.

In September 2019, an employee of the indigenous affairs agency was shot dead in Tabatinga, the largest city in the region.

The British embassy said in a statement that it is in contact with local authorities, and providing support to Mr Phillips’ family.

Maria Laura Canineau, director of Human Rights Watch in Brazil, said in a statement: “It is extremely important that Brazilian authorities dedicate all available and necessary resources to the immediate realization of searches, in order to guarantee, as soon as possible, the safety of the two men.”