The United States called on Iraq's government to stop using violence against protesters, reform its electoral system and hold early elections, after weeks of unrest in which security forces have killed about 300 protesters.

Washington wants "the Iraqi government to halt the violence against protesters and fulfil President [Barham] Saleh's promise to pass electoral reform and hold early elections," the White House said in a statement Sunday.

"The United States is seriously concerned by continued attacks against protestors, civic activists and the media, as well as restrictions on internet access, in Iraq," it said.

Mass rallies calling for an overhaul of the ruling system have rocked the capital Baghdad and the Shiite-majority south since Oct. 1, but political forces closed ranks this week to defend the government.

The protests were initially focused on a lack of jobs and services but quickly morphed into denunciation of the sectarian power-sharing system of government introduced in 2003 and the political elites they say benefit from it.