Peter Benenson, who died on Friday aged 83, was the founder of Amnesty International, the organization set up to put pressure on governments to release people imprisoned for voicing their political or religious opinions – people for whom Benenson coined the term “prisoners of conscience.”

The impetus for the founding of Amnesty was a newspaper article Benenson read in 1960: two Portuguese students had been arrested and sentenced to seven years in prison for drinking a toast to liberty – the government of Portugal was then in the hands of the dictator Antonio Salazar – at a cafe in Lisbon.

Incensed, Benenson, a barrister who already had experience with human rights work, came up with the idea of a one-year campaign to draw public attention to the plight of the world’s political and religious prisoners. His “Appeal for Amnesty 1961,” began: “Open your newspaper – any day of the week – and you will find a report from somewhere in the world of someone being imprisoned, tortured or executed because his opinions or religion are unacceptable to his government. The newspaper reader feels a sickening sense of impotence. Yet if these feelings of disgust all over the world could be united into common action, something effective could be done.”

As part of the campaign, Benenson published “Persecution 1961,” a short book that contained the stories of a handful of men and women from varying political and religious outlooks who had suffered imprisonment for expressing their opinions. By the end of that month Amnesty had accumulated 840 case files from 31 countries and the outlook was promising.

Amnesty took root and endured. By the start of the present century it had supporters in 160 countries and territories and had dealt with the cases of 47,000 prisoners of conscience and other victims of human rights violation. In 1977, the organization was awarded the Nobel Peace Prize.

Peter Henry James Benenson was born on July 31, 1921, a grandson of the Russian-Jewish banker Grigori Benenson. Peter’s father, a British Army officer, died young, leaving his widow, Flora, to bring up their son single-handed.

After being tutored privately by W.H. Auden, Peter went to Eton, where, moved by the sight of hunger marchers from South Wales passing through the town, he became a socialist. A complaint he made to the head master about the poor quality of the school’s food prompted a letter warning his mother of the boy’s “revolutionary tendencies.”

Undaunted, Peter took up the cause of Republican war orphans of the Spanish Civil War, and he managed to raise L4,000 from his school friends and their families to bring two young Jews to Britain from Nazi Germany.

After World War II, during which he served in the Army Intelligence Corps, Benenson became a lawyer and stood unsuccessfully for Parliament several times. He became a leading light in the Society of Labour Lawyers.

The Labour Party sent him to Spain as an observer at the trial of 17 Basque nationalists in 1954. He later sent observers to trials in Hungary in the wake of the uprising of 1956, and to South Africa.

Benenson stepped down as Amnesty’s leader in 1966, after an independent investigation did not support his claim that Amnesty was being infiltrated by British intelligence. But in the 1980s he returned to an active role as a speaker and campaigner on behalf of Amnesty – though he did not always agree with its policies.

A convert to Roman Catholicism, he was chairman of the Association of Christians Against Torture, and in the 1990s he organized help for Romanian orphans.

More than once he declined the offer of a knighthood.