BAGHDAD — Coordinated explosions ripped across seven Iraqi provinces on Monday, killing 64 and injuring 176 people in a sophisticated set of attacks that spread mayhem at security facilities from the Kurdish north to the Shiite south.

The attacks broke a month of relative calm and raised new questions about the effectiveness of the Iraqi security forces and the capabilities of their opponents just four months before U.S. forces are scheduled to have completely withdrawn from the country. U.S. and Iraqi officials are discussing whether some U.S. troops will stay on past the withdrawal date, now set for Dec. 31.

The Iraqi government declared a curfew in the wake of the blasts while Iraqi politicians criticized the security forces for not having stopped the attacks. Hakim al Zamili, a member of the Iraqi parliament's security and defense committee, said an investigation would be launched and that both provincial police officials and Iraqi military commanders would be questioned. "Those who are proved to be negligent" will be punished, he said.

A Kurdish lawmaker on the committee, Shwan Mohammed, said terrorist sympathizers had infiltrated the police and military and called for the security forces to be reorganized.

“The Iraqi security forces are penetrated, and the intelligence department can't provide information to prevent terrorist operations,” he said.

The explosions hit the provinces of Baghdad, Salauddin, Wasit, Najaf, Babil, Kirkuk and Diyala. The highest number of casualties was in Wasit, south of Baghdad, where at least 30 people died and 60 were wounded by two bombs that exploded near a downtown market, one after the other.

In Diyala province, northeast of Baghdad, 12 people were killed in two attacks that targeted an Iraqi checkpoint and a military camp. Twenty others were wounded.

In Babil, south of Baghdad, eight people were killed and 20 others were injured in Hindiyah when a parked car bomb detonated near a police station in the city.

In Najaf province, south of Baghdad, four people were killed and 20 wounded when a parked car bomb detonated near the Najaf police headquarters.

In Baghdad, three people were killed and 29 others were wounded in a series of explosions that included two car bombs. Two car bombs in Kirkuk, north of Baghdad, killed one and wounded 12.