Dom Phillips is still missing, and police are questioning him as the search for him in the Amazon forest enters its third day.

Dom Phillips, a veteran journalist, and Bruno Araujo Pereir, an Indigenous affairs official, went missing in the Amazon’s Javari Valley after being threatened by a group of men.

Police in Brazil are questioning a man in connection with the disappearance of a veteran British journalist who went missing in the Amazon rainforest.

International pressure is mounting on Brazilian authorities to act after Dom Phillips and an Indigenous affairs official, Bruno Araujo Pereir, went missing in the Javari Valley region more than three days ago.

A vigil for the two is being held outside the Brazilian Embassy in Central London, with protesters carrying large images of the missing.

This follows the arrest of a 41-year-old suspect for allegedly carrying a firearm without a permit, a common practice in the region.

Police did not say why he was being held as a suspect, but he is believed to have been among a group of men who threatened the couple near an indigenous territory on Saturday.

Mr Phillips, 57, a regular contributor to the Guardian, has been reporting from Brazil for more than a decade and was working on a book about Amazon conservation.

According to the Univaja association of people in the Vale do Javari indigenous territory, he photographed the men after the confrontation as they travelled by river to the territory’s borders.

The president of the association, Paulo Marubo, previously stated that the group brandished firearms at a Univaja patrol.

Four other people have been questioned since the investigation began, but no arrests have been made in connection with the disappearances, according to authorities.

The two men were supposed to arrive by boat in nearby Atalaia do Norte on Sunday morning, but they never arrived.

Indigenous leaders on the ground, as well as Mr Pereira’s and Mr Phillips’ family members and peers, have called for increased efforts to find them.

Greenpeace has organized the vigil in response to reports that authorities have provided little assistance in the search.