Doctors had said earlier on Tuesday they could do nothing but hope and pray for Klestil's survival after his heart twice stopped beating on Monday, triggering multiple organ failure.

"I'm sorry to have to inform you that the president, Dr Thomas Klestil, has died on July 6 at 11:33 p.m., due to a continuing deterioration of his inner organs," Dr Christoph Zielinski, the doctor leading the team treating Klestil at Vienna General Hospital, told a news conference.

Zielinski said Klestil's family was at his bedside when he died and declined to give any further details. Klestil was read the last rites on Monday.

Klestil, who in 1996 was hospitalized twice with breathing difficulties, was under sedation and on artificial respiration. He was due to step down on Thursday after two six-year terms and hand over his largely ceremonial post to Social Democrat Heinz Fischer.

Klestil won the respect, if not the affection, of Austrians for repairing much of the damage to the country's international image caused by revelations about former president and U.N. Secretary-General Kurt Waldheim's role in the German army under Adolf Hitler's Third Reich.

He was given much of the credit for normalizing Austria's relations with the rest of the world after Waldheim was ostracized by Western leaders and refused admission to the United States.

But the career diplomat also raised the eyebrows of many traditionalists in the Roman Catholic country when he began a relationship with a young aide, Margot Loeffler, prompting his wife of 37 years to walk out on him in 1994.

Klestil married Loeffler in 1998, shortly after being re-elected to a second term.

Klestil, a conservative like Chancellor Wolfgang Schuessel, was a critic of Schuessel's decision to forge a coalition with the far-right Freedom Party of Joerg Haider in 2000 -- a decision which resulted in eight months of international diplomatic sanctions against Austria.

Stony face

Klestil, who succeeded Waldheim in 1992, was also known for the famously stony face he maintained in February 2000 when swearing in the first Austrian government to include Joerg Haider's far-right Freedom Party .

"The Freedom Party is not a Nazi party," Klestil said in an interview at the time. "But unfortunately the highest officials of this party continue to use a language which disqualifies them for every political office."

But Klestil in the end did not use his constitutional powers to dismiss the government. Instead, he swore in the conservative and far-right ministers with a stern and unhappy look.

Born in 1932, the youngest of five children of a Vienna tram driver, Klestil spent 18 of his 35 years as a professional diplomat in the United States.

He went straight from university into the diplomatic service, first with Austria's mission to the Organization for Economic Cooperation and Development in Paris, then to the embassy in Washington as a junior diplomat.

He later served as Austrian ambassador to the United Nations and the United States.

After resigning from the diplomatic service, he was elected president in 1992 representing the conservative People's Party.

The head of state in Austria has mostly representative functions but his voice counts on important issues and he can influence the formation of a government.