The Brazilian president, Jair Bolsonaro, has said he believes “something wicked” was done to the missing British journalist Dom Phillips and the Brazilian Indigenous expert Bruno Pereira, amid unconfirmed claims their bodies had been found in the Amazon.

British relatives of Phillips said they had been contacted by the Brazilian embassy in London on Monday morning and informed that two unidentified bodies had been found during the search operation.

“He didn’t describe the location and just said it was in the rainforest and he said they were tied to a tree and they hadn’t been identified yet,” said Phillips’s brother-in-law, Paul Sherwood.

However, the federal police later denied the claims that two bodies had been found. Indigenous activists involved in the search effort also said they had no information about such a discovery but do believe the men’s remains will soon be found in an area of flooded forest where their search teams found some of the men’s belongings on Saturday.

Speaking to Brazilian radio on Monday, Bolsonaro said the evidence gathered by investigators suggested the two men, who went missing on the morning of 5 June while travelling by boat along the River Itaquaí, were unlikely to be found alive.

Bolsonaro said tests were being conducted on suspected human material found floating in one of the region’s rivers. “The indications are that something wicked was done to them,” the president added.

Personal items belonging to the two missing men were found in an area of flooded forest on Saturday thanks to a small but determined Indigenous search team that has spent the past seven days on the frontline of the search efforts.

As Brazil’s far-right leader spoke, hundreds of Indigenous protesters marched through Atalaia do Norte, the riverside town from which Phillips and Pereira set off on what was supposed to be a four-day reporting trip, on the afternoon of 2 June.

Carrying spears, wearing traditional dress and singing in their native tongues, the Indigenous protesters processed through the streets to demand justice and denounce the historic assault on Brazil’s environment and Indigenous lands that has played out since Bolsonaro took power in 2019.

“Bolsonaro’s no good – but God willing he will be defeated in [the] October [election,]” said Kura Kanamari, a leader from the Kanamari people from the Javari Valley Indigenous territory.

“We don’t want war with anyone. All we want is our peace and for our lands to be respected because our supermarket is in the lakes, the land and the forests. If this is all destroyed, our isolated relatives will go hungry,” Kanamari told demonstrators who had gathered in Atalaia’s main square, near the hotel where Pereira and Phillips had stayed before setting off on their trip.

Another Indigenous leader asked the crowd: “Why does the Bolsonaro government hate the Indigenous people so much? We never did anything to harm them.”

A third leader fumed: “Bruno has gone but all of us Indigenous people are still here and we are now Bruno and Dom Phillips.”

Beneath the stage demonstrators held posters and banners demanding: “Who killed Bruno and Dom” and “Bolsonaro out!” Another placard read: “Enough bloodshed of those who defend the Indigenous.”

Father Giuseppe Leoni, an Italian priest who has worked in the Amazon for more than 50 years, insisted the two men had not lost their lives in vain. Leoni said their dedication to helping Brazil’s Indigenous communities defend their forests and telling their stories to the world would inspire future generations of environmental and Indigenous defenders.

“They are a seed which has been cast out into the world and which will give the example of life,” the priest said of Phillips and Pereira.