Editors and journalists from some of the world’s biggest news organisations have written to the Brazilian president, Jair Bolsonaro, to ask that he “urgently step up and fully resource the effort” to find missing British journalist Dom Phillips and Brazilian Indigenous advocate Bruno Pereira.

Led by the Guardian and the Washington Post, two newspapers for whom Phillips worked as a freelance correspondent, editors from at least 20 major media and press freedom organisations signed the open letter that was published on Thursday.

Other signatories include senior editors from the New York Times, the Wall Street Journal, Folha de S.Paulo, National Public Radio, Bloomberg News, the Associated Press, the Financial Times, the Pulitzer Center, the Bureau of Investigative Journalism, ProPublica, The Intercept, Agência Pública de Jornalismo Investigativo, Dagens Nyheter, Mongabay, Stat, Reporters Without Borders, the Wallace House Center for Journalists and the epbr agency.

“We write to express our extreme concern regarding the safety and whereabouts of our colleague and friend Dom Phillips, and Bruno Araújo Pereira, with whom Dom was travelling. Dom is a globally respected journalist with a deep love for Brazil and its people,” said the letter, which was also addressed to Brazil’s defence and foreign ministers.

“As you will know from numerous press reports, Dom and Bruno have now been missing in the Amazon for more than three days. Their families, friends and colleagues have repeatedly requested assistance from local, state and national authorities and emergency services.

“As editors and colleagues who have worked with Dom, we are now very concerned by reports from Brazil that search and rescue efforts so far have been minimally resourced, with national authorities slow to offer more than very limited assistance.

“We ask that you urgently step up and fully resource the effort to locate Dom and Bruno, and that you provide all possible support to their families and friends.”

The two men were last seen on Sunday morning on the Itaquaí River in the far west of Brazil.

Phillips was working on a book on rainforest development and was accompanied by Pereira, an explorer who has worked with Indigenous tribes in the region for years.

The area where they went travelling is remote and the search effort was slow to get going. In the hours after the two men were reported missing the Brazilian military said it was awaiting orders before launching a search.

By Wednesday, as public pressure mounted amid campaigns by luminaries such as football legend Pelé, singer/songwriter Caetano Veloso and actor Camila Pitanga, officials said they had increased their operation, with 250 people, two planes, three drones and 16 vessels involved in the search.

Police announced they had arrested one man, who sources said had been seen with Phillips and Pereira, but officials said they had not tied him directly to any crime.

At the same time, press organisations united to put pressure on a government that has shown disdain for the media since taking power in 2019.

Brazil’s extremist president has frequently attacked the press, even singling out reporters with insults and abuse.

Bolsonaro even appeared to blame Phillips and Pereira for their own troubles when he called their reporting trip “an adventure that isn’t recommendable for anyone”.

In an editorial, the Guardian called on governments and organisations to put pressure on the far-right leader.

“The government is highly unlikely to change course without international pressure,” it said. “That must first be brought to bear to produce an adequate response to this disappearance.”

Full list of signatories to the letter

Katharine Viner, editor-in-chief, Guardian News & Media

Sally Buzbee, executive editor, the Washington Post

Dean Baquet, executive editor, the New York Times

Sérgio Dávila, editor-in-chief, Folha de S.Paulo

Nancy Barnes, senior vice-president of news and editorial director, NPR

John Micklethwait, editor-in-chief, Bloomberg News

Julie Pace, SVP & executive editor, the Associated Press

Juan Forero, South America bureau chief, Wall Street Journal

Marina Walker Guevara, executive editor, Pulitzer Center

Rozina Breen, editor-in-chief and CEO, the Bureau of Investigative Journalism

Stephen Engelberg, editor-in-chief, ProPublica

Paul Webster, editor, the Observer

Jason Ukman, managing editor, Stat

Thiago Domenici, director, Agência Pública de Jornalismo Investigativo

Rhett Butler, founder and CEO, Mongabay

Peter Wolodarski, editor-in-chief, Dagens Nyheter

Roger Hodge, deputy editor, the Intercept

Felipe Maciel, executive director, epbr agency

Phil Chetwynd, global news director, AFP

Roula Khalaf, editor, the Financial Times

Emmanuel Colombié, Latin America director, Reporters Without Borders

Lynette Clemetson, director, Wallace House Center for Journalists

Quinn McKew, executive director, Article 19

Jodie Ginsberg, president, Committee to Protect Journalists

Gregory Feifer, executive director, Institute of Current World Affairs

Lindsey Hilsum, international editor, Channel 4 News

Christina Lamb, chief foreign correspondent, Sunday Times

Krishnan Guru-Murthy, presenter Channel 4 News

Jon Lee Anderson, biographer and staff writer, the New Yorker

Leonardo Sakamoto, director, Repórter Brasil

Nelly Luna Amancio, editor-in-chief, OjoPúblico

Katia Brasil, executive director, Amazônia Real

André Petry, editor-in-chief, Revista Piauí

Jeffrey Goldberg, editor-in-chief, The Atlantic