At least 33 people were killed in attacks across Iraq on Wednesday that included a coordinated assault against local government and police buildings in the north of the country, police and medical sources said.
Militant groups including the Sunni Islamist al Qaeda have been regaining momentum in their insurgency against Iraq's Shi'ite-led government this year, reviving the spectre of the sectarian carnage of 2006-07.
In the northern town of Hawija, two suicide car bombs were detonated outside a local council building and a police station before militants fired mortar rounds and exchanged fire with the army, killing three soldiers, military sources said.
At least three assailants were also shot dead during the attacks, which military officials said looked like the work of al Qaeda. The militants withdrew after reinforcements arrived.
"I was at the Hawija local council building when suddenly two blasts shook the ground," said witness Yaseen al-Sabaw. "I ran out of the building and saw human flesh and body parts spread around the entrance".
Iraq's fragile sectarian balance has come under growing strain from the conflict in neighbouring Syria, where mainly Sunni rebels are fighting to overthrow a leader backed by Shi'ite Iran.
Al Qaeda's Iraqi wing merged with its Syrian counterpart this year to form the Islamic State of Iraq and the Levant, which has claimed responsibility for attacks on both sides of the border.
Nearly 6,000 people have been killed in violence so far this year, according to the monitoring group Iraq Body Count.
A bomb planted inside a wooden cart on a commercial street in the northern city of Mosul exploded on Wednesday evening, killing seven people, and a roadside bomb south of Tikrit killed five more, police said.
Gunmen opened fire at a vehicle in Taji, around 20 km (12 miles) north of Baghdad, killing two off-duty soldiers, police and medical sources said.
In Baghdad, gunmen broke into the house of a policeman in the Shaab district of northern Baghdad, killing him, his wife, his sister-in-law and his three children, police and medics said.
And a bomb planted in a commercial street in Baghdad's western district of Ghazaliya killed five others.