Irbil, Iraq ? A suicide car bomber wearing a police uniform killed at least 15 traffic policemen and wounded 100 others Monday during morning roll call at a police headquarters in this oil-rich northern Kurdish city, the second such attack in as many days.

The bombing that ripped through the police facility was one in a series of attacks, including at least five suicide car bombings, that swept Iraq Monday. Authorities reported 37 people died in attacks nationwide in the ongoing militant offensive that has killed nearly 1,200 in less than two months.

On Sunday, a suicide bomber walked into a Baghdad kebab restaurant popular with policemen and blew himself up, killing 23 people, including seven officers.

“Most of the attacks targeting the Iraqi security forces, including the police, are launched by Islamic fundamentalists,” said Sabah Kadhim, an Interior Ministry spokesman. “Their main aim is to keep the country in chaos.”

Jordanian-born Abu Musab al-Zarqawi, who leads al-Qaida in Iraq, purportedly gave his stamp of approval in an audiotaped message last month to the killing of fellow Muslims and civilians collaborating with the Shiite-led government and the United States.

Monday’s attack in Irbil was the largest in a day of violence that saw at least 37 people killed. One U.S. soldier was killed by a roadside bomb in northern Iraq.

The number of insurgent attacks has escalated since Prime Minister Ibrahim al-Jaafari announced his Shiite-led government on April 28. At least 1,189 people have been killed since then, according to an Associated Press count based on military, police and hospital reports.

A U.S.-led offensive dubbed Operation Spear ended Monday. It was launched last week with 1,000 Marines and Iraqi soldiers in western Anbar province to ebb the flow of foreign fighters entering from Syria. The four-day campaign in the border city of Karabilah, 200 miles west of Baghdad, killed about 60 insurgents. One Marine also died.

“The operation was very successful because we cleaned out some insurgent weapons caches, we found evidence of lots of foreign fighter involvement, and we fully integrated with the Iraqi security forces,” said Marine Lt. Col Tim Mundy of Waynesville, N.C., who commanded the operation.