By Daniel Schweimler BBC News

Former military officer Adolfo Scilingo, from Argentina, is being tried in Spain accused of human rights abuses in his native country, under the military government in power from 1976 to 1983.

He admitted dumping live prisoners into the sea from helicopters, although he is now on hunger strike, saying he retracts his statement.

Mothers of disappeared students have campaigned for decades

Mr Scilingo is the first defendant accused of such crimes to appear in a foreign court, where the prosecution is calling for a jail sentence of more than 6,000 years.

There are however cases pending against many others accused of crimes during the military's campaign against what they believed to be left-wing subversives.

The military came to power in Argentina in 1976 after a long period of political and social instability promising to restore order and tackle what they saw as the growing menace of a violent left-wing revolutionary group, the Montoneros.

They set about their task with some gusto, imprisoning trade union activists and student leaders. Any protest was met with overwhelming force.

Many soldiers believed they were fighting a civil war and pointed to the situation in neighbouring countries which also had military governments fighting left-wing unrest, most notably General Augusto Pinochet's Chile.

Torture centres

Government agents would arrive in the dead of night in cars with blackened windows and no registration plates and abduct suspects... sometimes picking up those who they decided looked suspicious or were merely in the wrong place at the wrong time.

Teenagers and pregnant women were among those taken away to be tortured and many thousands were never seen again.

Adolfo Scilingo operated in the most notorious of the detention and torture centres - the naval mechanics school, a building in a middle-class neighbourhood of Buenos Aires.

Official records show that 13,000 Argentines were killed during what became known as the Dirty War, although human rights groups say the figure was closer to 30,000.

The military government stood down in 1983 after their humiliating defeat by British forces over the Falkland Islands a year earlier. But the fight for answers has continued to this day, far from where the crimes took place.