The bombing of the Golden Mosque sparked a wave of sectarian violence that has so far claimed the lives of nearly 130 people across Iraq.
Al-Hakim, who heads the Supreme Council for the Islamic Revolution in Iraq, blamed Saddam Hussein loyalists and Al-Qaeda followers for the bombing.
A daytime curfew in Baghdad announced by Iraq's government is largely being observed with streets in the capital reportedly largely empty.
However, in Baghdad's predominantly Shi'ite neighborhood of Al-Sadr City, unidentified gunmen clashed with militiamen loyal to Shi'ite cleric Muqtada al-Sadr. It was not immediately clear whether anyone was killed.
(compiled from agency reports)