Mr Poch denies involvement in so-called "death flights"
A pilot held in Spain over his alleged role in Argentina's "Dirty War" will stay in detention pending a decision on extradition, a Spanish judge has ruled.
Julio Alberto Poch, an airline pilot, has been in custody in Madrid since his arrest last month.
He is wanted in Argentina for allegedly flying planes used to dump opponents of the military regime into the sea. He denies the allegations.
Some 30,000 people disappeared or died during the junta's 1976-1983 rule.
Mr Poch was held during a short stopover at Valencia's Manises airport on 22 September, while flying an aircraft for Dutch Transavia airlines, a subsidiary of Air France-KLM.
DIRTY WAR CONVICTIONS
Ex-President Jorge Videla: Serving a 1985 life sentence for the murder, torture and detention of hundreds
Ex-naval officer Adolfo Scilingo: Given 640 years in prison in 2005 for involvement in death flights
Ex-General Santiago Omar Riveros: convicted in 2009 for murder; his intelligence chief and four others jailed
Ex-police chief Miguel Etchecolatz: serving a 2006 life sentence for kidnap, torture and murder
The 57-year-old, who has dual Dutch and Argentine nationalities, is said to have been a military pilot at Argentina's notorious Naval Mechanics School - one of the biggest torture and detention centres of the Argentine military regime.
He is alleged to have been involved in the so-called "death flights", in which political prisoners of Argentina's military were drugged and dumped into the sea from the planes.
Mr Poch's lawyers requested his release at Tuesday's closed-door hearing in a high-security court in Madrid.
Lawyer Ignacio Pelaez Marques told AFP news agency that his client denied ever having been based at the Naval Mechanics School.
Mr Pelaez said the judge had decided his client should remain in custody until a decision was made about extradition to Argentina, because of the gravity of the allegations he faces.
In 2005, Argentina's Supreme Court struck down amnesty laws which had shielded alleged human rights abusers from prosecution.