"The curfew will be in force again Saturday until 4 pm in the capital and Salaheddin, Diyala and Babil provinces," an announcement on state television said.
Prime Minister Ibrahim Al-Jaafari ordered Friday’s curfew in the capital and three surrounding provinces to cool sectarian unrest which has claimed 130 lives in two days.
Most of the dead are Sunni Muslims in reprisals against the Sunni Arab minority who are blamed for bombing the revered Shi'ite shrine in Samarra.
Since the curfew there have been a few sporadic incidents but no new large scale killings have been reported.
“Moment of Choosing”
US President George W. Bush tried to downplay fears of an all out civil war on Friday but said that Iraq faced "a moment of choosing" between sectarian violence and democracy.
"We can expect the coming days will be intense. Iraq remains a serious situation. But I'm optimistic," Mr Bush said pointing to elections that he said showed Iraqis wanted to build a democracy.
President Bush and other US defence officials urged Iraqi leaders to build a unity government that would not marginalise the minority Sunni Muslims. He also dismissed claims that the country was falling apart.
Senior Pentagon officials backed the president’s view that Iraq was not spiraling into civil war but admitted that sectarian violence was one of the toughest tests yet for the country’s political process.
"What the extremists are trying to do is to foment a civil war. But we don't see it. We don't see it succeeding," said Peter Rodman, assistant secretary of defence.
Mr Rodman said the US is anticipating resumed negotiations between Iraqi leaders on forming a new government, which broke off after the mosque bombing.
"We expect the formation of the government to resume. And that is the strategic prize," he said. "Not only do I not see civil war happening, I don't think they're going to succeed in derailing the political process," Mr Rodman said.
Iraqi progress report
It comes as the Pentagon delivered to Congress a quarterly progress report on Iraq, completed just days before the latest wave of sectarian violence, warning of a potential increase in sectarian violence.
Completed on February 17, before the Shi’ite shrine bombing, the report stated that: "ethno-sectarian attacks may increase in an effort to provoke reprisals."
But the report, at the time of completion, remained confident that attacks perpetrated by insurgents were failing to cause their desired effect. "Terrorist groups have so far failed to create widespread sectarian conflict, despite this being a clear goal of some," it said.
The report did concede that thousands of Shiites had been killed over the course of the year in suicide attacks by al-Qaeda in Iraq and that Shiite-controlled Interior Ministry security forces have attacked and detained Sunnis.