The Spanish government has given the green light for an indicted former Argentine junta officer, Ricardo Cavallo, to be extradited to Argentina.
Ricardo Cavallo has been held in a Spanish prison since 2003
Mr Cavallo is accused of killing and torturing left-wing activists in the "dirty war" of 1976-1983.
It is not yet clear when he may be sent back to Argentina.
He was extradited to Spain from Mexico in 2003. Up to 30,000 people are said to have been killed or disappeared in Argentina during the "dirty war".
Mr Cavallo had been living for years in Mexico under an assumed name. His case is being handled by a leading anti-terrorist investigator, Judge Baltazar Garzon.
Spanish law allows offences committed abroad to be tried in Spain if a suspect is not facing prosecution in his home country.
The ex-naval commander has been charged by Spanish authorities with genocide and terrorism, which he denies.
The government's decision on Friday contradicts a July 2007 Supreme Court ruling that Mr Cavallo should go on trial in Spain.
Mr Cavallo served at the notorious Navy School of Mechanics in Buenos Aires, a detention centre in which hundreds of people were tortured and killed.
At least 614 people were held at the navy school during the military campaign against left-wing insurgents. Many were drugged and thrown from aircraft into rivers and the sea.
Spanish prosecutors have requested multiple life sentences in prison for Mr Cavallo, for the death and torture of Spanish citizens.