BAGHDAD A suicide bomber blew himself up at a police checkpoint west of Baghdad on Saturday, killing at least 10 people including the local police chief, an official said.
Fearing more attacks, authorities imposed a vehicle ban and closed all entrances to the targeted town of Hit.
The attacker detonated his explosives belt after approaching the checkpoint, which was near a bridge, at about 9 p.m., said the town's administrator, Hikmat Jubeir.
Jubeir said six policemen were among those killed, including the town's police chief Col. Khalil Ibrahim. Four civilians also were killed and 12 other people were wounded, he said.
Hit, 85 miles west of Baghdad, is in Anbar province, which was the center of the Sunni-led insurgency before local tribal leaders joined forces with the U.S. military against al-Qaida in Iraq, a key factor in a steep drop in violence nationwide.
The town itself was among a series of communities along the Euphrates River used by al-Qaida and other insurgent groups to smuggle weapons, ammunition and fighters from Syria southeast toward Baghdad.
The bombing was a grim reminder of the dangers that continue to face Iraqis despite the recent security gains.
It raised the number of Iraqis killed in May to at least 532, the lowest monthly death toll this year, according to an Associated Press tally compiled from Iraqi police and military reports.
In political developments, loyalists of radical Shiite cleric Muqtada al-Sadr stepped up their opposition to a long-term security deal being negotiated between the Iraqi government and the United States.
Senior Sadrists, including lawmakers Falah Hassan Shanshal and Maha Adel al-Douri, met in the cleric's Sadr City office in Baghdad and called on the Iraqi government to stop the negotiations and to hold a public referendum on the issue.
Al-Sadr, the hardline Shiite cleric whose Mahdi Army militia battled U.S.-Iraqi troops in Baghdad's Sadr City district until a truce this month, also has called for a referendum along with weekly protests against the deal.
Widespread opposition among the Sadrists and other Shiite and Sunni groups has raised doubts that negotiators can meet a July target to finalize a pact to keep U.S. troops in Iraq after the current U.N. mandate expires at the end of the year.
Although U.S. officials insist they are not seeking permanent bases, suspicion runs deep among many Iraqis that the Americans want to keep at least some troops in the country for many years.
Tensions also rose when Nassar al-Rubaie, the leader of the Sadrist bloc in parliament, was stopped at a police checkpoint outside Diwaniyah, south of Baghdad.
The six-car convoy, en route from Basra to the holy city of Najaf, was held up for nearly two hours without explanation, al-Rubaie told The Associated Press in a telephone interview. He called for the government to stop harassing Sadrists and put those responsible on trial.
Police Col. Asaad Ali, the director of the Diwaniyah operations center, said police stopped the convoy because gunmen are not allowed in the city and al-Rubaie was protected by armed guards. He said a patrol was sent to safely escort the convoy on its way out of the province.
Despite the truce, the U.S. military has continued to target what it calls Iranian-backed Shiite militia factions, warning key leaders have fled to other areas as American and Iraqi forces closed in on them in Sadr City.
American troops acting on tips in eastern Baghdad on Saturday captured a suspect believed to be a key assistant to one of the fugitive militia leaders, according to a military statement. The man captured was accused of kidnapping and managing funds for the so-called special groups.
The U.S. military also said an American Marine died Friday in a non-combat related incident in Iraq, pushing the number of Americans killed this month to 21 as May draws to a close.
While the number is not final, it would be the lowest monthly death toll since February 2004, when 20 troops died, according to an Associated Press tally based on military figures.
Separately, French Foreign Minister Bernard Kouchner expressed renewed commitment to helping the Iraqis rebuild as he made his second visit to the war-torn country in less than a year.