An explosives-laden car parked near an outdoor market exploded Sunday in a mainly Sunni area in western Iraq, killing at least five people and wounding 34, police said, raising concern that sectarian violence could resurge now that U.S. troops have pulled out of major Iraqi urban areas.

The attack came as Shiite Prime Minister Nouri al-Maliki was visiting the self-ruled Kurdish region in northern Iraq for talks with Kurdish leaders over a range of issues that have long poisoned relations, like control of oil and territory.

Al-Maliki recently said in Washington that differences between the Kurds and the rest of Iraq were among the most dangerous challenges facing his country and that they must be resolved by constitutional means, not by force.

On Sunday, he met with recently re-elected regional President Massoud Barzani, Iraqi President Jalal Talabani, a Kurd, and other Kurdish officials.

But Sunday's bombing — coming two days after 29 people were killed in blasts in Baghdad — demonstrated that Iraq continues to be volatile elsewhere as well, and raised concerns about the abilities of Iraqi forces to protect the people as U.S. troops prepare to withdraw by the end of 2011.

A police officer said the explosives-laden car was parked near sidewalk vendors at an outdoor market in Haditha, a city on the Euphrates 140 miles northwest of Baghdad. The officer gave the casualty toll on condition of anonymity because he wasn't authorized to release the information.

Haditha is in Anbar province, which was one of the most dangerous areas in Iraq until Sunni tribal leaders joined forces with the U.S. military to fight Al Qaeda in Iraq.

The attack Sunday follows a series of blasts in the capital Baghdad over the past few days.

A bomb hidden inside a toilet struck a Sunni mosque south of Baghdad on Saturday, wounding two people, according to Iraqi police. A series of bombings targeted Shiite mosques a day earlier during Friday prayers in Baghdad, killing at least 29 people and injuring more than 100.

U.S. officials have warned they expect insurgents to try to re-ignite sectarian violence, which pushed the country to the brink of civil war in 2006 and 2007. Violence has dropped sharply following a U.S. troop surge in 2007, a Sunni revolt against Al Qaeda in Iraq and a Shiite militia cease-fire.

U.S. officials have said they were optimistic that Shiite groups would exercise restraint in the face of Sunni attacks targeting their community. Bombings blamed on Sunni insurgents have often in the past been followed by mortar attacks and execution-style retaliatory killings.