The military governor of the Falkland Islands during Argentina's brief occupation of the archipelago in 1982 was detained for his alleged role in human rights abuses at a torture centre in the 1970s, prosecutors said.
Former General Mario Benjamin Menendez was arrested at his home in Buenos Aires and transferred to a federal prison in Tucuman province, 800 miles north of Argentina's capital.
The 82-year-old Menendez was briefly governor of the Falklands, which are called the Malvinas in Latin America, after Argentina occupied the islands.
It subsequently lost control when British troops retook the islands in 1982.
Prior to that, Menendez was a general in the Argentine armed forces.
His arrest relates to La Escuelita, a torture centre in Tucuman province that he allegedly helped run in 1975, the year before the military coup that ushered in Argentina's 1976-1983 dictatorship, the attorney general's office said.
Prosecutors said he was head of the Tactical Command Post at the centre.
A unit of the Revolutionary People's Army operated in the mountains of Tucuman in 1974, and the civilian government in power at the time ordered a crackdown on the group.
Prosecutors say 1,507 suspects passed through the centre between February 10 and December 18, 1975, part of a systematic campaign of repression against dissidents and leftists ahead of the coup.
Besides Menendez, 21 other people have been arrested across Argentina in connection with the case. Among them is a cousin of Menendez, former Colonel Jose Maria Menendez, who is under house arrest.