Bombings and shootings killed more than 32 people across Iraq on Sunday, underscoring the government's struggle with a stubborn insurgency more than nine months after the last U.S. troops withdrew.
In Taji, 20 km (12 miles) north of the capital Baghdad, bombs in three parked cars went off separately, killing 11 people and wounding 24, including several policemen.
Reuters footage of the scene of one of the explosions showed the remains of an exploded car surrounded by several completely and partially destroyed houses and cars.
Taji has one of Iraq's largest military airbases but the bombing hit a civilian neighbourhood.
"A car bomb entered the area and no one... noticed this. Why did that happen? All the houses were destroyed," said Khadiar Abas, owner of one of the damaged homes.
In Baghdad, a suicide car bomb and two parked car bombs went off, killing eight people including a police officer and wounding another 11.
Another blast targeted a bus carrying Iranian pilgrims as it passed through the town of Madaen, about 30 km (20 miles) southeast of Baghdad, killing two passers-by and wounding another ten, including seven Iranians.
A suicide bomber in a car blew himself up in the city of Kut, 150 km (95 miles) southeast of Baghdad, killing four policemen, police and local officials said.
No group claimed responsibility for the raft of attacks, but a local al Qaeda affiliate and other Sunni Islamist groups have carried out at least one major assault a month since the last American troops left in December.
Al Qaeda's local wing, the Islamic State of Iraq, says it has begun a new offensive against mainly Shi'ite targets. Security experts say it has benefited from the conflict in Syria, which has given al-Qaeda the pretext to seek more money and arms from Sunni tribes, politicians and governments.
Security had been tightened in Baghdad and other provinces after dozens of inmates, including convicted members of al Qaeda, fought their way out of a prison in the northern city of Tikrit on Friday using weapons officials said had been smuggled in during family visits.
Two more policemen were killed when a car bomb went off in the town of Balad Ruz, 90 km (55 miles) northeast of Baghdad.
In Mosul, 390 km (240 miles) north of Baghdad, a parked car bomb and two roadside bombs blew up separately, killing a civilian and wounding six.
The last major attacks occurred on Sept. 9, in the capital when a series of bombs in mainly Shi'ite districts ended one of the bloodiest days of the year with more than 100 killed across the country.
Violence in Iraq has eased since its height in 2006-2007 when sectarian fighting killed thousands of people, but Sunni Islamists are still seeking to undermine the Shi'ite-led government.