During the dark days of the military dictatorship in Argentina in the 1970s, there was only one newspaper that dared to publish the names of the “disappeared” – let alone to put them every day on the front page, as Andrew Graham-Yooll did as news editor of the Buenos Aires Herald.

Graham-Yooll, who has died aged 75, nearly paid with his life for such audacity. In 1976 he and his first wife, Micaela Meyer, got out just in time – “out of the back door and straight to the airport”, as he put it – as the men in the black Ford Falcons came looking for him. He never wanted to go into exile but had little choice other than to resettle in London until the generals – “those bastards” as he referred to them – were removed from power by a combination of the Falklands war and economic incompetence.

His best and most acclaimed book, A State of Fear: Memories of Argentina’s Nightmare (1986), was about those years of the 1976-83 military dictatorship, and was described by Graham Greene as a masterpiece. It is easy to see why Greene liked it so much. Over 12 discrete episodes Graham-Yooll captures the surreal nature of the conflict and the accommodations that a journalist has to make when there are no frontlines, only back rooms: tea with a rightwing torturer who made chilling confessions; a clandestine encounter with a leftwing guerrilla on the run. (She tells him, bitterly, while pointing a gun at him: “You’re in the middle, but not neutral; you’re right in the middle of this mess” – and then takes her clothes off.)

In London Graham-Yooll contributed to newspapers and then found he could reinvent himself as a writer, and the books started to flow. In 1994 he returned to Argentina, becoming editor-in-chief of his old paper.

Graham-Yooll was born in Buenos Aires and grew up in the suburb of Ranelagh, as part of the English-speaking community, the son of an English mother, Inés (nee Tovar), and a Scottish father, Douglas Graham-Yooll, who had emigrated from Leith in 1928. After a turbulent childhood – Inés died when he was five and Douglas when he was 19, and at one point he ran away from home – Andrew joined the Buenos Aires Herald, Argentina’s English-language newspaper, in 1966, achieving rapid promotion under the editorship of Bob Cox.

After a military coup in 1976 brought the generals to power, both men came to the attention of the rightwing junta for their reporting of a growing wave of “disappeared” – around 30,000 men and women of the left who went missing without notice during what became known as “the dirty war”.

As the military refused to give any account of these executions – the bodies were often dropped into the River Plate from planes – it needed courage and persistence to cut through the official version that many of these victims had gone into hiding or fled to Europe. But Graham-Yooll always played down the idea that he and his colleagues at the Herald had been fearless in putting names into print. “Of course we were afraid,” he said, “but it’s one thing to be afraid and another thing to be a coward.”

After escaping to London he was given a job by the Telegraph and then was able to return briefly to Buenos Aires in 1982 as a correspondent for the Guardian, covering the Falklands war. Despite having what he thought was journalistic immunity, he was assaulted one night by members of the Argentinian security services when walking near the Torre de los Ingleses in Buenos Aires.

He continued to write as a freelance for various British newspapers, and became editor of the international magazine South in 1985. He was also closely involved with the freedom of speech organisation Index on Censorship, along with Stephen Spender and others, and edited its magazine from 1989 to 1993.

He became a prolific author, writing more than 30 books in English and Spanish. Before A State of Fear he had produced Small Wars You May Have Missed (1983), an attempt to educate an anglophone public about the history of South American conflicts, many of which Britain had played a pivotal role in instigating. He also proved himself to be a historian, a poet and a fine literary critic: his book After the Despots: Latin American Views and Interviews (1991) is one of the best works on South American magic realism writers.

In 1992 Graham-Yooll went back to Buenos Aires to make a BBC film about Argentina during the junta era, called War Stories, which I directed and so came to know him. His spell in the country suggested that conditions were now propitious, so he moved back full-time, soon becoming editor-in-chief and then president of the board at the Buenos Aires Herald, where he worked until 2007.

A quiet, modest and self-deprecating man when speaking English, he could become far more passionate in Spanish: I once saw him cry when he was listening to Carlos Gardel’s tango anthem Volver, not least because its lyrics about re-encountering a first love after many years of absence were so apposite to his own return to Argentina. On another occasion he took me to an alley behind the Hurlingham club in Buenos Aires, where the bodies of the disappeared had once been dumped, and expressed the slow-burning anger about those events that had stayed with him for the rest of his life.

In 2002 he was made OBE.

He is survived by his second wife, Maria (nee Niero), whom he married shortly before his death, his children, Inès, Luis and Isabel, from his 1966 marriage to Micaela, which ended in divorce in 1999, an adopted son, Matias, seven grandchildren and his sister, Joanne.

• Andrew Graham-Yooll, journalist and author, born 5 January 1944; died 6 July 2019