Argentina’s former dictator General Leopoldo Galtieri is being held at a military jail on the orders of a judge prosecuting human rights abuses.
Argentina's de facto president during the 1976-83 dictatorship led the country to war with Britain over the Falkland Islands.
Gen Galtieri is accused of taking part in the abduction, torture and execution of some 20 leftist guerrillas and other dissidents.
The 72-year-old general was the third of four presidents to serve during the military's rule.
He was picked up at his suburban Buenos Aires home and driven under heavy guard to the jail on the city's outskirts.
Federal Judge Claudio Bonadio also ordered the arrest of 42 other former military and state security officials, including General Carlos Guillermo Suarez Mason and former army chief General Cristino Nicolaides.
Both men presided over military battalions accused of widespread atrocities during the seven-year dictatorship.
Gen Galtieri's arrest revives public scrutiny of a dark chapter in which some 9,000 leftist dissidents were officially reported as killed or missing after a systematic state crackdown. Human rights groups put the toll at up to 30,000.
Thousands of dissidents were drugged and thrown alive from aircraft into the sea or rivers. Others were buried in secret graves which have still not been found and babies were stolen from pregnant detainees who were then killed.
Gen Galtieri was appointed president in November, 1981, and eight months later ordered Argentine troops to invade the Falkland Islands, which Argentina claims it inherited from the Spanish crown.
AP