TEHRAN: The attackers who stormed Tehran´s parliament complex and the revolutionary leader´s shrine on Wednesday were Iranian nationals who had joined Daesh, a top official said.

The six attackers "were Iranian and joined Daesh from some parts of Iran," said Reza Seifollahi, deputy secretary of Iran´s Supreme National Security Council, on state TV late Wednesday.

It was the first attack in Iran claimed by Daesh, which had threatened to step up its campaign in the country in recent months.

Iran is a key fighting force against Daesh and other groups in Iraq and Syria.