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.

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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.