At least 40 people were wounded in the wave of bombings, which struck the northern oil city of Kirkuk and towns just north of the capital as well as Baghdad, security officials said.
At least eight of the bombs exploded in Baghdad wounding about 32 people, security officials said.
Two car bombs also exploded in the northern city of Kirkuk wounding four civilians, police said.
Two more car bombs exploded in towns just north of Baghdad Insurgents also shot dead a policeman in the main northern city of Mosul and wounded two more in a roadside bombing to its east.
An official of the Assyrian Democratic Movement was killed by gunmen in the south Baghdad neighbourhood of Dura, the Christian political party said.
Gunmen also killed two worshippers and wounded five as they left a Sunni mosque after evening prayers.
Further south, in the town of Mahmudiyah, a Shiite cleric belonging to the radical movement of Moqtada Sadr was shot dead by suspected Sunni Arab insurgents.
The US military also confirmed a soldier had been killed in a New Year's Eve mortar attack in south Baghdad.
Fuel riots
In Kirkuk, persistent fuel shortages in the oil city sparked rioting in which one person was killed and four wounded, prompting the authorities to impose an overnight curfew.
Protestors torched two petrol stations and a building housing the offices of the state oil company as well as police vehicles.
US helicopters hovered overhead but ground troops stationed not far away did not intervene.
Police commander Brigadier-General Munis Isahak said the authorities had no choice but to impose a 12-hour curfew in a bid to restore order.
"The citizens have a right to protest but these have turned violent and people have been hurt," he said.
Fuel supplies to a vast swathe of northern and central Iraq have been badly hit by a 10-day-old action by truck drivers at the region's main oil refinery in the town of Baiji to protest death threats from Sunni Arab insurgents.
In a separate protest in the southern oil centre of Basra, at least 1,000 people burned tyres in protest at increases in pump prices.
In the latest attack on oil installations, rebels blew up an oil pipeline near a Baghdad oil refinery, sparking a large-scale fire.
"This attack has affected production at the refinery, which can handle 110,000 barrels a day, but it has not stopped production," said oil ministry spokesman Assim Jihad.
The spokesman said a few deliveries of refined products had resumed from Baiji after some of the striking drivers returned to work.
Hostages released
In the Mediterranean island of Cyprus, relatives of food and drink dealer Garo Jikerjian, who also has Lebanese nationality, were celebrating his release after five months in captivity in Iraq.
"This was the best Christmas present I could ever expect, it's like no other," said Jikerjian's aunt, Rita Metzadourian, who added that she had spoken to him briefly and that "he said he was okay."
"I believe there was payment made," she added. "They wouldn't have released him otherwise but I don't know any of the details."
The Cypriot foreign ministry said it had been informed by the family that Jikerjian, who is of Armenian origin, had been freed on December 31 and would return to the island in the next few days.
Lebanese engineer Camille Nassif Tannus, who had been abducted on Thursday, was also freed, Lebanon's official ANI news agency said.
He was "in good health" and back at his home in Baghdad, it said citing a dispatch to the foreign ministry from charge d'affaires Hassan Hijazi.
The Sudanese authorities meanwhile announced that five nationals, including a diplomat, who had been seized by gunmen as they left a Baghdad mosque on December 23, had been freed by their captors.
They were in good health, foreign ministry spokesman Jamal Mohammed Ibrahim told the official SUNA news agency in Khartoum.
The release of the five hostages by militants loyal to Al-Qaeda came after Sudan agreed to close its Baghdad embassy as demanded by the kidnappers.