Brazilian police said on Monday they had found the boat in which British journalist Dom Phillips and his Brazilian expert guide Bruno Pereira were travelling before they were killed in the Amazon.

The boat was found Sunday night some 20 meters underwater and 30 meters from the right bank of the Itaquai River, packed with six sandbags to keep it submerged, federal police said in a statement.   

The vessel will now be searched for clues.

Veteran correspondent Phillips, 57, and Pereira, 41, went missing on June 5 in a remote part of the rainforest rife with illegal mining, fishing and logging, as well as drug trafficking.

Ten days later, on Wednesday, a suspect named Amarildo da Costa de Oliveira - known as "Pelado" - took police to a place where he said he had buried bodies near the city of Atalaia do Norte, where the pair had been headed by boat.    

Human remains found at the spot were brought to Brasilia for examination and confirmed to belong to the two missing men.   

On Saturday, police said they had been shot.   

'Powerful criminal organisation'

A third suspect handed himself over to police, and told investigators where to find the boat.  

A boat engine and four drums belonging to Pereira were also found, the police statement said.

Five more people believed to have been involved in concealing the bodies have been identified, it added. 

Last week, police said the men's killers had acted on their own initiative and not as part of a criminal group - a conclusion rejected by the Univaja Indigenous association, which had participated in the search. 

Univaja claims that "a powerful criminal organisation... planned the crime down to the smallest detail". 

Phillips, a longtime contributor to The Guardian and other leading international newspapers, was working on a book on sustainable development in the Amazon with Pereira as his guide when they went missing.  

Pereira, an expert at Brazil's indigenous affairs agency FUNAI, had received multiple threats from loggers and miners with their eye on isolated Indigenous resources.  

Univaja said it had reported evidence to the authorities that "Pelado" was involved in illegal fishing and had been involved in gun attacks against a FUNAI base.  

Experts say illegal fishing of endangered species in the Javari Valley takes place under the control of drug traffickers who use the sale of fish to launder drug money.