Militants shot dead five Iraqi soldiers in the Sunni Muslim stronghold province of Anbar on Saturday and protesters said they were forming an "army" after four days of unrest that raised fears of a return to widespread sectarian civil conflict.
More than 170 people have been killed since Tuesday when security forces stormed a Sunni protest camp in the town of Hawija, triggering clashes that spread to other Sunni areas in western and northern areas.
Sunnis have been demonstrating since December against the perceived marginalization of their sect under Iraq's Shi'ite Muslim-led government.
A curfew was imposed on the city of Ramadi in Anbar, a western province, on Saturday after militants killed five soldiers who authorities said were returning from holiday to their units. Protesters said they had been sent to attack them.
Protests had eased recently, but the army raid earlier this week in Hawija, near the city of Kirkuk, 170 km (100 miles) north of Baghdad, reignited Sunni discontent and may have given fresh impetus to insurgents.
"In order to keep Anbar a safe place for the Sunnis, we decided to form an army called the Army of Pride and Dignity with 100 volunteers from each tribe to protect our province," said Sheikh Saeed Al-Lafi, a spokesman for the protesters.
Lafi said police and members of the Iraqi army were welcome to join their ranks.
Influential Sunni cleric Sheikh Abdul Malik Al-Saadi, who had previously taken a conciliatory stance and urged restraint, on Saturday congratulated the "honorable Iraqi mujahideen (holy warriors)" on the proclaimed creation of the regional army.
At least four members of a government-backed Sunni "Sahwa" militia were killed when gunmen opened fire at a checkpoint in Awja, outside Tikrit. Police and militants battled in Baiji, a former bastion of Sunni jihadist al Qaeda, about 180 km (112 miles) north of Baghdad.
In the Abu Ghraib district of Baghdad, four soldiers were killed early on Saturday in clashes with unidentified gunmen.
KURDISH TROOPS DEPLOY
Relations between the central government and ethnic Kurds, who run their own administration in the north, have also been frayed by an ongoing row over land and oil rights.
Kurdish security forces deployed beyond the formal boundary of their autonomous region overnight, a move they said was to protect civilians in the oil-rich territory over which both the Kurds and Baghdad claim jurisdiction.
At the heart of that disputed area is the ethnically mixed city of Kirkuk.
"After the incident in Hawija created an unstable situation in the area, especially around Kirkuk city and ... all disputed areas ... military units mobilized from their bases," spokesman Jabbar Yawar said on his Facebook page.
The Iraqi army and Kurdish troops, known as peshmerga, are facing off along their contested internal boundary following a military build-up late last year.
Yawar said the deployment was based on information that "terrorists" were planning to take advantage of the volatile situation to carry out attacks in the area, but said the peshmerga had no plans to enter Kirkuk or any other cities.
"There are no political intentions behind this plan. The sole objective is to protect the lives and possessions of civilians," Yawar said.