He was serving a life sentence for treason and several appeals to free him were rejected by successive governments.

His last years were spent in failing health in a heavily guarded hospital room.

Mr Papadopoulos headed what was known as the regime of the colonels - a group of military officers who seized power in a coup in 1967.

He ruled Greece with an iron hand until 1973 when he was deposed as self-appointed president by the armed forces.

Military rule collapsed after provoking an unsuccessful coup in Cyprus which led to the Turkish invasion of the island.

Death sentence

After the restoration of democracy he was sentenced to die by firing squad for treason but later ordered to spend the rest of his life in jail.

A decision by the government to free him on humanitarian grounds in December 1990 was dropped after a public outcry and protest by opposition parties.

He spent most of the last three years in hospital.

"During the past month his health rapidly deteriorated. His organs failed and he died in the intensive care unit a few hours ago," a hospital doctor said.

Communist threat

He was born into a poor family in the northern Peloponese village of Eleochorion.

In 1940 he graduated first in his class at the Military Academy.

During the German occupation in World War II he fought in the resistance.

A short, stocky man with a bristly moustache and rapid-fire oratory, he gained a reputation as a fierce anti-communist.

He once accused ex-US President Richard Nixon and two-thirds of the American Congress of being communists.

And guards at Athens Korydallos maximum security prison said he never regretted his role in the coup, "insisting to the last moment that he saved Greece from communism".

The European Commission on Human Rights later asserted that no communist threat ever existed.

And it also said his regime tortured prisoners as a matter of policy and denied fundamental human rights to citizens.