The widely respected international civil servant Prince Sadruddin Aga Khan, who has died of cancer aged 70, was never able to repeat the achievements of his 12 years as United Nations high commissioner for refugees (UNHCR), and failed in two attempts to be elected UN secretary-general. In later years, he used his standing and wealth to promote environmental causes.
Arguably much of Sadruddin's life was spent trying to prove that his father Aga Khan III had misjudged him when he decided against allowing him to inherit the imamate, and spiritual leadership, of the widely dispersed Shia Ismailis, and had instead named as heir his grandson Karim - Sadruddin's nephew - who became his successor in 1957. The formidable old Aga Khan had apparently felt that Sadruddin would remain a playboy. Sadruddin rarely showed his disappointment. He respected Karim; but the two never became very close and, just occasionally, he betrayed his feeling that life had been unjust.
Prince Sadruddin was born in Paris. His mother was French, his father had lived his early life in India but was of Iranian descent, and had acquired British nationality. Sadruddin saw himself as a citizen of the world - a multilingual, highly cultured cosmopolitan, familiar with the upper echelons of international society, who nevertheless became passionately involved with the plight of successive and growing waves of refugees and the seemingly insoluble problems of resettlement.
He was educated at Le Rosay, Switzerland's elite school, and Harvard. Soon after Harvard he married the glamorous Nina Dyer, and the couple did the rounds of the world's social scene. But they divorced in 1962, and Sadruddin's lifestyle changed.
His first brush with UN institutions reflected his knowledge of Nubian art. He became an adviser to the UN educational, scientific and cultural organisation (Unesco), which was embarking on its project to save Nubian monuments threatened by the construction of the Aswan Dam.
But at the same time, Sadruddin was, in 1958, made an adviser to the UNHCR, rising to the role of deputy high commissioner in 1962 and high commissioner in 1966. He was highly effective, as an administrator and above all as an advocate, able to cajole, shame and persuade governments to provide tolerable funding as crisis after crisis created more and more refugees.
He was high commissioner when Pakistan broke up in 1971-72 and the new nation of Bangladesh had to resettle hundreds of thousands of refugees. In 1973 Idi Amin evicted the Asians from Uganda - including many Ismailis - who had to be resettled. That same year there were refugees from Pinochet's Chile and, in 1974, the breakup of Cyprus, with refugees moving in both directions from the Greek and Turkish parts of the island.
Sadruddin's UN refugee work continued after he ceased to be high commissioner. Most notably he was made coordinator for UN humanitarian and economic assistance programmes in Afghanistan between 1988 and 1990; and he was brought in after the Gulf war in 1990-91 to provide humanitarian assistance, especially to the Shi'ites in Iraq.
He barely dented the refugee problems in either case. In Afghanistan, he asserted that the west had little interest in the return of refugees and was too busy helping the mojahedin. In Iraq, he insisted that UN sanctions had to be lifted if Saddam Hussein was to be persuaded to behave more humanely. This did not gain him any acclaim, even though George Bush Sr was a firm friend, and indeed was prepared to back Sadruddin in his quest for the UN secretary-generalship in 1991.
He had first sought the post in 1981, when the Soviet Union made clear that it would veto his candidacy. In 1991, Russia had no need to threaten a veto. It was obvious that Sadruddin would be unable to secure the required majority.
Sadruddin then turned much of his energies into his Bellerive Foundation to promote environmental causes. He also organised seminars on global development problems, devising strategies for lessening the gap between rich and poor. He was preoccupied by the moral dimensions of effective intervention to promote peace and preserve global life.
Sadruddin was helped and encouraged by his second wife, Catherine, whom he married in 1972. She is a strict vegetarian, and while guests at his Lake Geneva chateau could count on excellent fare, host and hostess often ate brown rice and salads.
Sadruddin was always an Ismaili, but he did not dwell much on his religious beliefs. He was concerned with morals and ethics, and tolerance was an essential part of his credo. He was a good man who believed in the duty of elites to improve the lot of humanity.
· Prince Sadruddin Aga Khan, international civil servant, born January 17 1933; died May 12 2003