Brazilian Federal Police arrested three more suspects in a case arising from the slaying of a journalist and an Indigenous expert in the remote western reaches of Brazil's Amazon rainforest.

A police statement alleges the three were involved in the hiding of the bodies after the killing. It said they are relatives of Amarildo da Costa Oliveira, known as "Pelado," a fisherman who is one of three men previously charged with murdering the victims.

British journalist Dom Phillips, 57, and Brazilian Indigenous expert Bruno Pereira, 41, were killed on their boat on the Itaquai river, near the entrance of the Javari Valley Indigenous Territory, which borders Peru and Colombia.

A total of seven people have been arrested for alleged involvement in the killings or the attempted coverup.

Federal police officers arrive at the pier after recovering human remains found during a search for Indigenous expert Bruno Pereira and freelance reporter Dom Phillips. Photo / AP

Prosecutors have said the three men charged with murder in the case are fishermen who killed Phillips and Pereira because the pair asked to photograph the suspects. The area is a hotspot for illegal fishing and poaching.

In an investigation that has grown out of the murder case, police also identified a man arrested in early July for allegedly carrying false documents as Ruben Dario da Silva Villar, known as the "Colombian." A Colombian citizen, he was using a Brazilian identity card and also a Peruvian document, the statement said.

Federal police officers load body bags onto a police vehicle. Photo / AP

The statement described him as the "leader and financier of an armed criminal association dedicated to the practice of illegal fishing in the region of Vale do Javari, which was responsible for commercialising a large amount of fish that was exported to neighbouring countries."

In addition to the three people arrested for suspected involvement in hiding the bodies of Philips and Pereira, two other people were arrested in the investigation of illegal fishing, police said.

- by Debora Alvares, AP