Thousands of Iranians have taken to the streets of Tehran to condemn the killings of hundreds of Shiite Muslims in Nigeria and demanded the release of a Nigerian Shiite leader.

Hundreds of Shiites were reportedly killed in an army raid in Nigeria last Saturday. Shiite leader Ibraheem Zakzaky suffered four bullet wounds and was taken into custody.

Human rights groups say as many as 1,000 people may have been killed.

Demonstrators at Friday's rally in Tehran carried banners demanding Zakzaky's "unconditional release."

Iran, seen as the guardian of the Shiite Muslim faith, has condemned the killings. The Foreign Ministry summoned the Nigerian charge d'affaires earlier this week to protest the killing in Zaria, in northern Nigeria.

The Nigerian military said it acted after Shiites tried to assassinate Nigeria's army chief.