BAGHDAD - Insurgents carried out attacks across a broad swath of central and northern Iraq on Thursday, including a motorcycle suicide bombing and three car bombings, killing at least 33 people and wounding dozens of others.

The strikes were the latest in a series of assaults that began Sunday and that appear to be in response to an ambitious counterinsurgency effort led by the Iraqi government, in which tens of thousands of Iraqi security forces have been assigned to police the streets of Baghdad.

Much of the violence earlier in the week unfolded in western Baghdad, but most of the deadly attacks on Thursday took place outside the capital, as the insurgency, largely led by Sunni Arabs, appeared to be seeking to apply pressure to the Shiite- and Kurdish-led government.

The American military said Thursday that three soldiers died Wednesday in separate incidents in northern and western Iraq.

In the capital, officials on a Shiite-led committee of the National Assembly overseeing the writing of a constitution met Thursday with frustrated Sunni leaders to discuss how Sunnis might play a bigger role in the process. Since a visit last month by Secretary of State Condoleezza Rice, Shiite officials have been saying they intend to broaden Sunnis' role in the process in hopes of calming the insurgency and drawing more Sunnis into the political system.

Contributing to ongoing tensions, Sunni Arabs have accused a Shiite militia of assassinating Sunni Arab clerics. But in an interview with The Associated Press, Interior Minister Bayan Jabr, who once played a leading role in the militia, the Badr Brigade, denied the claim, which he said had been investigated.

Mr. Jabr also said that more mosques and clerics from the Shiite majority had been attacked than those belonging to the Sunni minority, and that 80 percent of the roughly 12,000 Iraqi civilians killed in the past 18 months were Shiites.

In the deadliest single attack on Thursday, insurgents gunned down nine people in a bazaar in Huriya, a northwestern Baghdad neighborhood. The insurgents drove up in three sedans and opened fire at shoppers, an Interior Ministry official said. It was not known why this particular market was attacked.

On Thursday morning, a car bomb exploded outside a restaurant in the town of Tuz Khurmato, about 60 miles south of the contested city of Kirkuk, killing at least 8 people and wounding 22 others, the Interior Ministry official said. The bomb was aimed at a convoy of bodyguards assigned to protect Rowsch Shaways, a deputy prime minister and a senior member of one of the two main Kurdish parties. Mr. Shaways who was not with the convoy at the time.

The Army of Ansar al-Sunna, a militant group active in the north, posted an Internet message claiming responsibility.

In Kirkuk, a suicide car bomb exploded near a convoy carrying foreign oil workers as it entered a compound that houses oil technicians, killing an Iraqi child standing nearby and injuring 11 other people, the Interior Ministry official said.

Also in the morning, a suicide car bomb exploded in the city of Baquba, 35 miles northeast of Baghdad, next to a convoy carrying Hussein Alwan al-Tamimi, the deputy chief of the provincial council, killing Mr. Tamimi and three of his guards and injuring four policemen, the Interior Ministry official said.

Al Qaeda in Mesopotamia, the group led by the militant Abu Musab al-Zarqawi, claimed responsibility on the Net for the latest attack.

Far to the north, in the beleaguered city of Mosul, a suicide motorcycle bomb exploded at 3:45 p.m. on Thursday at a traffic light in the city center, killing at least 7 people and injuring at least 10 others, said Mishal Rahoo, an employee in the local health department.

The explosion took place near the headquarters of the Mosul police force, which may have been the target. Though suicide car bombs have been common in Iraq, the use of motorcycles for such a purpose is rare.

A roadside bomb blast in Mahmudiya, a town in the Euphrates valley south of Baghdad, killed three people and wounded three others, and in southern Baghdad, insurgents attacked a police patrol with a car bomb and gunfire, killing a female bystander and injuring another civilian and a policeman, The Associated Press reported.

Among the American casualties on Wednesday, one soldier died of injuries from gunfire near Ramadi, in Anbar Province, the military said Thursday. Another was killed by a roadside bomb near Ramadi, and a soldier in Kirkuk died of injuries not related to combat, a military spokesman said, adding that American officials had begun an investigation.