The spiritual leader of Iraq's Shi'ite majority has called for the creation of a new, "effective" government.
In a message delivered by his representative, Ayatollah Ali al-Sistani said the future government "should open new horizons toward a better future for all Iraqis."
Speaking on behalf of Sistani, Abdul-Mahdi al-Karbalaie also said Sunni extremists who have overrun swaths of territory must be expelled from Iraq before it is too late.
Karbalaye said in Karbala on June 20 that Iraqis of all religions and communities should come together to fight the Sunni extremists.
He said a previous call by Sistani for Iraqis to join the armed forces "was for all citizens, without specifying a religion."
The extremists led by the Islamic State of Iraq and the Levant (ISIL), an Al-Qaeda splinter group, have exploited Sunni Arabs' anger at their perceived discrimination by the Shi'ite-led government to gain support.
President Barack Obama on June 19 said that the United States would send up to 300 military advisers to help in the fight against the militants.
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Obama said no U.S. troops would be returning to fight in Iraq.
Iraq's army was thrown into disarray after ISIL (also known as ISIS) launched its offensive in the north of the country earlier this month, capturing Mosul, Iraq's second-largest city.
Iraq's government has asked for U.S. air strikes against the militants.
Obama said he was prepared to take "targeted" military action "when and if" necessary.
But he insisted there was no military solution and called on the government to be "inclusive."
Reports said Iraqi security forces on June 20 were still engaged in fighting with the militants at the Baiji oil refinery north of Baghdad, despite claims by the government that its forces were in "full control" there.
Officials and witnesses said the crew of an Iraqi helicopter killed a civilian when they apparently mistook a police patrol for insurgents and opened fire.
The incident took place in Duluiya, a town north of Baghdad seized by the militants last week but subsequently retaken by government forces.
With reporting by Reuters, AP, and AFP