Maria Becket: Resistante who fought the Greek junta then became an ecological activist

Becket was physically and morally courageous – and imperious: one glance could bring a room to order

Maria Becket was a lifelong fighter for justice and sanity. Sometimes she fought by persuasion, as when she organised a decade of "symposium" voyages to confront the international elite with the growing threat to the world's waters. But sometimes, above all in resistance to the Greek military dictatorship between 1967 and 1974, she took part in clandestine armed struggle, including the smuggling of weapons and explosives. It was hard to believe that this dignified lady bore on one leg the scar of a grenade ill-thrown during guerrilla training in Syria.

As a child during the Nazi occupation she carried resistance leaflets across starving Athens in her doll's pram, and once opened the front door to find a dead girl her own age huddled on the step. "Why her? Why not me?" was her first political thought. Her father Nikolaos Chary, a famous civil engineer, was involved in resistance, but his experiences in the horrific civil war which followed the occupation eventually drove him to suicide.

Maria came to fear his violent and authoritarian behaviour. Her mother's family was very different. The Dzelepys came from Constantinople; their Greece was the lost Hellenic world of the Byzantine Empire, and the blood of the imperial Palaeologos dynasty ran in their veins. The family were at first shocked when Maria married an American, the radical film-maker Jim Becket. But when their daughter Sandra was born, on 15 August 1961, the Dzelepys' hearts melted: it was 700 years to the very day since their ancestor Michael Palaeologos had recaptured Byzantium from the Venetians.

Maria was a schoolgirl on holiday when she met Count Folke Bernadotte on the island of Rhodes. It was 1948, and the Count – a UN mediator in Palestine – was to be murdered by Zionist gunmen only a few weeks later. But they had time to become friends, and his answers to her impatient questions about the fate of the Palestinians later served her well.

For a time, Maria seemed to be entering a conventional life. She did a doctorate in London, married Becket and became the mother of two little girls. But then, in April 1967, a clique of right-wing officers and politicians overthrew democracy in Greece. Censorship, mass arrests and torture followed.

It was now that Maria Becket discovered her two great political talents: for persuasion and for conspiracy. She became a familiar figure at the United Nations as she lobbied tirelessly against recognition or acceptance of the Greek dictatorship. In 1969, the evidence of torture produced by Maria through victims she had smuggled out of Greece secured the expulsion of Greece from the Council of Europe. In secret, she organised the smuggling of arms and explosives to the resistance inside Greece.

She persuaded Yasser Arafat, the Palestinian leader, to offer Greek partisans weapons training in his Syrian camps. Maria was in Damascus in July 1974 when the junta launched its disastrous coup in Cyprus, leading to the flight of Archbishop Makarios, the Turkish seizure of half the island and the collapse of the junta itself. With Palestinian help, Maria set up Radio Free Cyprus in an olive grove near Beirut and broadcast messages from Makarios to reassure his followers that he was still alive. Soon she was back in Cyprus organising international aid for the flood of Greek refugees fleeing from the Turks. Democracy returned to Athens, but Maria turned down an offer to become Greece's ambassador to the United States. Instead, she used resources left over from the anti-junta campaign to rescue Turkish dissidents opposing their own government.

In the later part of her life, Becket took up the cause of the world's waters against the "new apocalypse" of pollution and exploitation. In 1995 she organised the first of eight hugely ambitious "symposium" voyages, carrying ecologists, clerics of all creeds, bankers, EU Commissioners and environmental commentators on chartered ships to study a threatened sea or river. Formalised as the charity Religion, Science and the Environment, the symposia visited the Aegean, the Black Sea, the Danube, the Adriatic, the Baltic, the Amazon, the Greenland Arctic and the Mississippi Delta. Becket was working on a Ganges Symposium during her final illness.

The shipboard patron of RSE was Bartholomew I, the Ecumenical Patriarch of Constantinople and formally the senior prelate of the Orthodox churches. Within a few years, his enthusiasm for "the natural creation" had earned him the media title of "The Green Patriarch". But while the credit for recruiting and promoting him lies with Becket, her motives may have been as much political as pious. The Dzelepy clan had always been loyal to the Constantinople Patriarchs because they were the last authentic Byzantine officials. Maria may have hoped not only to strengthen Bartholomew's position in Turkish Istanbul, but through him to unite the whole Orthodox world community in action to save the environment.

From her small Athens flat, Becket carried the burden of organising the symposia almost single-handed. She began life as a rich woman, but as the banking crisis discouraged donors, she began to spend her own money. By the time of her final illness she was almost penniless. It was a cruel irony that as she lay dying, panicky Greek tax authorities tried to accuse Religion, Science and the Environment of money-laundering.

She was imperious; one glance from her huge, black eyes could bring a noisy room to order; in constant pain from a scoliosis which made her limp, she was both physically and morally courageous. An outer darkness of scorn awaited those who disappointed her. She could allow herself to be warm, tender and often very funny with those closest to her, especially her daughters Sandra and Daphne and her beloved granddaughter Sophia. But Maria ultimately set duty above personal happiness, and through her bold acts and inflexible persistence she left the world a cleaner place.

Maria Becket, social and political activist: born Athens 7 April 1931; married Jim Becket (two daughters); died Athens 29 October 2012.