Argentina has begun extradition procedures for a man accused in Spain of being a top leader of the violent Basque separatist group ETA, a court official said yesterday. The official, who asked not to be named, said the foreign office had begun the extradition procedure after receiving a request from Madrid. Argentine police arrested Jesus Lariz Iriondo, wanted in Spain on suspicion of attacking a police car in 1984 and injuring two people, last week. A Spanish Interior Ministry spokesman pegged him as one of the outlawed group's most important leaders in South America. ETA commanders wanted in Spain commonly flee to Latin America. Iriondo was arrested in neighboring Uruguay in July but was then expelled to Argentina on Friday where he was immediately detained at Buenos Aires' airport. The reasons for the expulsion to Argentina were not clear. ETA has killed more than 800 people since 1968 to press its demands for an independent state in Basque areas of northern Spain and southwestern France. Iriondo is under investigation for belonging to an armed group, aggravated robbery, property damage and arms possession.