The Spanish consul in Tehran, Ignacio Pérez Cambra, was detained by police officers for four hours on Monday during violent protests in the Iranian capital.
The diplomat was arrested by six plain-clothes officers outside the official Spanish diplomatic mission, diplomatic sources told Spanish news agency Efe. The reason for his arrest was still unclear at press time.
Tehran was the scene of a number of demonstrations yesterday, which saw thousands of opposition supporters clash with Iranian security forces in several parts of the city.
The police used tear gas against the protestors and detained dozens of those present, who were out on the streets in a show of solidarity with the recent uprisings seen in Tunisia and Egypt.