A former federal police officer, he is accused of committing crimes at a secret prison where he was a specialist in fighting what the military called "subversive elements".
Former police officer Mario Sandoval, accused of crimes against humanity during Argentina's "Dirty War" four decades ago, was arrested by French police on Wednesday after years of legal tussles, a lawyer representing the Argentine government said.
The lawyer, Sophie Thonon-Wesfreid, told Reuters he was arrested just hours after France's top administrative court, the Conseil d'Etat, rejected Sandoval's appeal against his extradition. He was being held near Paris.
Sandoval, who moved to France after the fall of Argentina's seven-year military dictatorship and obtained French citizenship in 1997, is accused by Argentine prosecutors of more than 600 human rights violations including torture.
He denies the charges.
As many as 30,000 people were murdered in Argentina during the 1976-1983 dictatorship's so-called Dirty War against suspected leftists and political dissidents, according to human rights groups.
Sandoval's attorney was not immediately available for comment.
France's highest civil and criminal court Cour de Cassation and the French government authorized in 2018 Sandoval's extradition to Argentina to face charges of crimes against humanity. Sandoval filed an appeal to the Conseil d'Etat after those decisions.