Jorge Videla, 85, ruled Argentina from 1976 to 1981 and was considered the architect of a ruthless "dirty war" to eliminate armed left-wing guerrillas and their supporters.

The regime is held responsible by human rights groups for making some 30,000 people "disappear," with many of them thrown from aircraft into the sea during night-time flights.

The 31 prisoners he was convicted of killing were pulled from civilian jail cells and "shot while trying to escape" as the military consolidated its power in the months after Videla toppled Isabel Peron.

"Videla ... is a manifestation of state terrorism," judge Maria Elba Martinez said as she handed down the sentence in the central Argentine city of Cordoba.

The former dictator remained unrepentant, telling the court the day before his sentencing that Argentine society had demanded the crackdown to prevent a Marxist revolution and claiming that the country was now run by "terrorists".

Videla also defiantly told the court that he was a political prisoner and denied human rights violations despite saying he accepted "full responsibility" for his actions as his subordinates were only following orders.

He was ordered to be detained for the rest of his life in a federal jail under civilian rather than military rules, denying him any special privileges.

Videla was previously tried and sentenced to life in prison in 1985 but was pardoned five years later by the then-president, Carlos Menem. Three years ago a court ruled that the pardon was unconstitutional, paving the way for the latest trial.

Argentina's military government fell in 1983, a year after Videla's successor, Leopoldo Galtieri, waged an unsuccessful war against Britain for the Falkland Islands.