Video of protesters cheering in the night as flames billowed from the consulate were a stunning image after years in which Tehran's influence among Shi'ite Muslims in Arab states has been a defining factor in Middle East politics.

More than 50 others were wounded, mainly by live bullets and tear gas canisters, in clashes across Baghdad, the sources added.

More than 250 people have been killed so far since the protests first erupted last month as security forces moved in to contain the increasingly violent rallies.