BAGHDAD - A suicide car bomber targeted the provincial police headquarters in Mosul yesterday, killing at least nine people and wounding dozens, police said. The attack underscored fears that Sunni insurgents are regrouping despite a U.S.-Iraqi offensive in the northern city.

No one claimed responsibility for the attack, but suicide operations are commonly associated with al-Qaeda in Iraq - the main target of U.S.-Iraqi military operations to clear the city 225 miles northwest of Baghdad.

Salim Shakir said he was walking toward his house in the area when he was hit with shrapnel.

"We are shocked because we thought that the violent days had ended," the 47-year-old taxi driver said from his hospital bed. "This explosion shows that the insurgents are still active, and much is needed to stop them."

The U.S. military has said al-Qaeda in Iraq is on the run but retains the ability to conduct its trademark high-profile car bombings and suicide attacks. U.S. and Iraqi troops have faced relatively little resistance since launching the offensive May 10, but commanders warn that many key insurgent leaders have fled to outlying areas and are planning attacks.

Yesterday, the attacker detonated his explosives-laden car about 8 p.m. as he approached a checkpoint allowing cars through concrete blast barriers surrounding the headquarters, in a busy commercial district.

Five policemen and four civilians were killed, while 46 people were wounded, according to a police officer, who spoke on condition of anonymity because he was not authorized to release the information.

The blast highlighted the fragility of recent security gains even as the Iraqi government struggles to take advantage of the relative calm in the country to make political progress.

Iraqi lawmakers said yesterday that they were stepping up negotiations on a draft law setting rules for provincial elections, due to begin in October. They warned that failure to reach agreement within the next two weeks may lead to a delay in the key vote to redistribute power among Iraq's fractured parties.

The elections to choose councils for Iraq's 18 provinces are seen as an important step in repairing the country's sectarian rifts, particularly by opening the door for greater Sunni Arab political representation.

Many Sunnis boycotted the last election for provincial officials in January 2005, enabling Shiites and Kurds to win a disproportionate share of power at their expense - even in areas with substantial Sunni populations.

Followers of anti-U.S. cleric Muqtada al-Sadr also are hoping to make large gains in southern provinces, where many of the councils are dominated by rival Shiite parties in the ruling government coalition.

But disputes have arisen over organizational details in the draft law, such as the way candidates will be presented to voters.

Iraq's Independent Election Commission has said the law must be passed by June 1 for it to have time to organize the vote before the Oct. 1 deadline.

A delay means parliament will have to pass a separate law pushing back the election to November or December - which would be a setback for U.S. efforts to get Iraqi politicians to overcome differences.