The trial has begun of Argentina's last military ruler, Reynaldo Bignone, and five other retired generals.

The men are charged in connection with the alleged kidnapping, torture and disappearance of 56 opponents of the military government in the late 1970s.

The abuses are alleged to have taken place at the Campo de Mayo base on the outskirts of the capital, Buenos Aires.

Human rights groups say up to 30,000 people were killed or disappeared in Argentina between 1976 and 1983.