* Bombs target mostly Sunni mosques in capital
* Big Sunni demonstrations in western province
* U.N. envoy urges restraint after days of clashes
Bombs planted outside Baghdad mosques killed eight more people on Friday at the end of a week of bloodshed that prompted a United Nations envoy to warn Iraq was "at a crossroads".
At least 150 people have been killed since Tuesday, when troops stormed a Sunni protest camp, triggering clashes that quickly spread to other Sunni areas in western and northern provinces.
Although well below the heights of 2006-7, this week's violence was the most widespread since U.S. troops pulled out of Iraq in December 2011. Militant attacks have increased this year as Iraq's fragile ethnic and sectarian balance comes under growing strain from the civil war in neighbouring Syria.
"I call on the conscience of all religious and political leaders not to let anger win over peace, and to use their wisdom, because the country is at a crossroads," U.N. envoy Martin Kobler said in a statement.
Tens of thousands of Sunni Muslims poured onto the streets of Ramadi and Falluja in the western province of Anbar following Friday prayers, in their biggest show of strength since the outbreak of protests last year.
In Ramadi, about 100 km (60 miles) west of Baghdad, the preacher, who wore military fatigues with his cleric's turban, gave security forces 24 hours to quit the city, warning he would not be responsible for whatever happened after that.
Iraqi Sunnis have been protesting since December against what they see as the marginalisation of their sect since the U.S.-led invasion overthrew dictator Saddam Hussein in 2003 and empowered majority Shi'ites through the ballot box.
The demonstrations had recently eased, but this week's army raid on a protest camp in Hawija, near Kirkuk, 170 km (100 miles) north of Baghdad, reignited Sunni discontent and appears to have given fresh momentum to insurgents.
In Baghdad, a roadside bomb exploded near the Sunni Kubaisi Mosque, killing four worshippers as they left after Friday prayers, police and medics said.
Another Sunni mosque was targeted by a roadside bomb in the Rashidiya district north of Baghdad, killing two people, and a soldier was killed in a separate explosion outside Shahid Yousif mosque in the Shaab neigbourhood.
Also in Shaab, a bomb killed one person outside a Shi'ite mosque, police and medics said.
No group claimed responsibility for any of the attacks, but Iraq is home to a number of insurgent groups including a local wing of al Qaeda.
In the town of Suleiman Pek, 160 km (100 miles) north of Baghdad, militants who seized control on Wednesday pulled back after reaching an agreement with the security forces and the governor of Salahuddin.
"We withdrew from these places in order to avoid bloodletting of our people because we know that the army wants to commit a new massacre similar to what happened in Hawija," tribal leader Jamil Al-Saqr told Reuters.