By Kamal Namaa

(Reuters) -

Fighting broke out when Iraqi police moved to dismantle a Sunni Muslim protest camp in the western Anbar province on Monday, leaving at least 13 people dead, police and medical sources said.

The camp has been an irritant to Prime Minister Nuri al-Maliki's Shi'ite Muslim-led government since Sunni protesters set it up a year ago to demonstrate against what they see as marginalization of their sect.

Maliki, who is seeking a third term in April elections, has repeatedly vowed to remove the camp and accused protesters of stirring strife and sheltering al Qaeda-linked militants.

Violence has spiked this year as al Qaeda-linked militants target the government and anyone seen to be supporting it, raising fears of a return to the sectarian conflict of 2006-7 that killed tens of thousands.

Police sources said Monday's clashes broke out when gunmen opened fire on police special forces trying to enter Ramadi, the western city where the protest camp is located.

Gunshots and blasts were heard in parts of the city. The gunmen destroyed four police vehicles and killed at least three policemen in the north of Ramadi, one source said.

The bodies of 10 other people killed in the clashes were brought into Ramadi's morgue, hospital and morgue sources told Reuters

In Falluja, gunmen attacked army patrols deployed along the main highway leading to Ramadi.

Sheikh Abdul Malik Al-Saadi, an influential Sunni cleric who had previously called on protesters to remain peaceful, denounced the operation and called on security forces to withdraw immediately to prevent further bloodshed.

Calling Maliki's government a "sectarian government that wants to smash and eradicate the Sunni people in its country," he urged Sunni ministers, parliament members and local officials to resign and boycott the political process.

The United Nations called for restraint.

"I am concerned about the current developments in Anbar and call on all to remain calm and to abide by the agreements reached in the course of the last two days," U.N. envoy to Iraq Nickolay Mladenov said in a statement.

RESENTMENT

Defense ministry spokesman Lieutenant-General Mohammed al-Askari told state television the decision to remove the camp came after tribal leaders and local government and defense ministry officials reached a deal.

Tensions have been rising over the past few weeks in Anbar, a province that makes up a third of Iraq's territory and is populated mainly by Sunnis living along the Euphrates River.

The army launched a major operation in Anbar to flush out al Qaeda militants after an attack killed at least 18 soldiers including an army commander on December 21.

Then on Saturday security forces arrested a prominent Sunni lawmaker in the area after killing his brother in a firefight with his bodyguards.

The incident prompted Saadi, the Sunni cleric, to urge Sunni protesters to prepare to "defend themselves.

Many Sunnis resent Shi'ite domination of Iraq's politics since the U.S.-led invasion that toppled Saddam Hussein in 2003 and empowered majority Shi'ites through the ballot box.

The invasion was followed by an insurgency that brought Iraq to the brink of civil war.

More than 8,000 people have been killed across Iraq this year, according to the United Nations.

(Reporting by Kamal Namaa in Ramadi and Ahmed Rasheed in Baghdad; Writing by Alexander Dziadosz; Editing by Andrew Heavens)