BAGHDAD, Iraq (Reuters) - More than 30 people were killed in gun battles between Iraqi forces and militants on Wednesday, a day after a raid on a Sunni Muslim protest ignited the fiercest clashes since American troops left the country.
The second day of fighting threatens to deepen sectarian rifts in Iraq where relations between Shi'ite and Sunni Muslims are still very tense just a few years after inter-communal slaughter pushed the country close to civil war.
The clashes between gunmen and troops were the bloodiest since thousands of Sunni Muslims started protests in December to demand an end to what they see as marginalization of their sect by Shi'ite Prime Minister Nuri al-Maliki.
On Tuesday, troops stormed one of the Sunni protest camps and more than 50 people were killed in the ensuing clashes which spread beyond the town of Hawija near Kirkuk, 170 km (100 miles) north of Baghdad, to other areas.
Sporadic battles continued on Wednesday and hardline tribal leaders warned that protests could turn into open revolt against the Baghdad government even as Sunni moderates and foreign diplomats called for restraint.
Militants briefly took over a police station and an army base and burned a small Shi'ite mosque in Sulaiman Pek, 160 km (100 miles) north of Baghdad, before army helicopters drove gunmen out of the town.
At least 18 were killed, including 10 gunmen and five soldiers, officials said.
An ambush on an army convoy near Tikrit with roadside bombs and rocket-propelled grenades killed three more soldiers. Three more troops were killed in an attack in Diyala province.
Later on Wednesday, clashes erupted in the northern city of Mosul, where gunmen launched an attack after using a mosque loudspeaker to call Sunnis to join their fight. At least three police and four soldiers died in the assault, officials said.
In a separate attack, at least eight people were also killed and 23 more wounded when a car bomb exploded in eastern Baghdad, police and medical sources said.
A surge in Sunni militant unrest has accompanied growing turmoil among the Shi'ite, Sunni and Kurdish parties that make up Maliki's power-sharing government.
A decade after the U.S.-led invasion, sectarian wounds are still raw in Iraq, where just a few a years ago violence between Shi'ite militias and Sunni Islamist insurgents killed tens of thousands of people.
Sectarian bloodshed reached its height in Iraq in 2006-2007 after al Qaeda bombed the Shi'ite Askari shrine in Samarra, triggering a cycle of retaliation.
Thousands of Sunnis have been protesting since December, venting frustrations building up since the overthrow of Saddam Hussein and the empowerment of Iraq's Shi'ite majority through the ballot box.
"We are staying restrained so far, but if government forces keep targeting us, no one can know what will happen in the future, and things could spin out of control," said Abdul Aziz al-Faris, a Sunni tribal leader in Hawija.
The two main Shi'ite militias, Asaib al-Haq and Kataeb Hizbullah, appear to have stayed out of the latest violence. But former fighters said they could take up arms again if needed.
Maliki has set up a committee headed by a senior Sunni leader to investigate the violence at the Hawija camp, which left 23 people dead. He has promised to punish any excessive use of force and provide for victims' families.
The prime minister has offered some concessions to Sunni protesters, including proposed reforms to tough anti-terrorism laws, but most Sunni leaders say they will not be enough to appease the demonstrators.
The Shi'ite premier may also seek to consolidate his position before 2014 parliamentary elections by taking a tough stance against hardline Sunni Islamists.
That may be a risk which could further alienate Sunnis.
"What we are now likely to see in western Iraq is a deteriorating cycle of confrontation between the central government and protesters that will benefit extremist groups," said Crispin Hawes at Eurasia Group.
Iraq's Sunni community is deeply divided between moderates more keen to work within Maliki's government and those who see resistance as the only way to confront Baghdad.
"The Maliki government's aggression against our people in Hawija has forced us to take our uprising on another course," said Sheikh Qusai al-Zain, a protest leader in Anbar province.
"We call upon all tribes and armed groups to begin supporting our brothers in Hawija."
Additional reporting by Ahmed Rasheed in Baghdad,; Gazwan Hassan in Samarra and Mustafa Mohammed in Kirkuk; Editing by Jon Hemming