Brazil firefighters say divers have found a backpack and laptop in a remote part of the Amazon where British journalist Dom Phillips and Indigenous expert Bruno Pereira went missing a week ago.

The backpack was tied to a tree that was half-submerged, a firefighter told reporters in Atalaia do Norte, the closest city to the search area, which is near the Javari Valley Indigenous Territory. It is the flood season in the region and part of the forest is flooded.

Officers with the Federal Police brought the items by boat to Atalaia do Norte later on Sunday afternoon.

Brazil Amazon
A Federal Police officer takes pictures of a seized boat during the search for British journalist Dom Phillips and Indigenous affairs expert Bruno Araujo Pereira (Edmar Barros/AP)

The local Indigenous association, with which Mr Pereira was working at the time of his disappearance, confirmed that firefighters’ divers found a backpack but said it could not immediately say to whom it belonged. The area has only poor riverside communities, where equipment like laptops are rare.

Previously, police found traces of blood in the boat of a fisherman who is under arrest as the only suspect and organic matter of apparent human origin inside the river. Both materials are under forensic analysis, and no more details were provided.

Brazil Amazon
The army, the navy, civil defence, state police and Indigenous volunteers have been mobilised in the search (Edmar Barros/AP)

Mr Pereira, 41, and Mr Phillips, 57, were last seen near the entrance of the Indigenous territory, which borders Peru and Colombia. They were returning alone by boat on the Itaquai river to Atalaia do Norte but never arrived.

That area has seen violent conflicts between fishermen, poachers and government agents. Violence has grown as drug trafficking gangs battle for control of waterways to ship cocaine, although the Itaquai is not a known drug trafficking route.