A group of about 30 armed men attacked a police checkpoint in Buhriz, 65km northeast of Baghdad on Monday, killing five policemen and injuring four, police said.
The raid, involving mortar, anti-tank and small arms fire, targeted a checkpoint in Buhriz, 60km northeast of the capital.
Police said six of the attackers were killed when police officers returned fire.
In the village of Dhabab, 100km from Baghdad, five soldiers were killed by armed men while leaving for work or during their morning routine in separate but apparently coordinated attacks, the army said.
Two US soldiers were killed in two separate attacks in Baghdad on Christmas Day (Sunday), the US army announced on Monday.
A press release by the US army said one soldier was killed in a roadside bomb explosion and the other by an improvised explosive device.
A university professor, Nofal Ahmed, was killed by armed men outside his home.
Police said they had also recovered the bodies of three people killed in and around Baghdad, including that of a policeman.
Bombs struck Iraqi police and army patrols and destroyed a US Abrams tank in Baghdad on Sunday.
The tank was left in flames after a dawn attack in eastern Baghdad. Witnesses said it had been destroyed by a roadside bomb.
Two soldiers were killed and six wounded in a mortar attack on an Iraqi base at al-Mahmudiya, just south of the capital.
In total, four car bombs went off in quick succession across Baghdad. Two policemen and a civilian were wounded when one of them, in a parked car, exploded near an Iraqi police patrol in the Karada neighbourhood, an Iraqi Interior Ministry source said.
Details of casualties in the other blasts were not immediately available.
Violence returned to several
cities soon after the elections
In Kirkuk, where Arabs, Kurds and Turkmen are vying for control of the northern oilfields, a civilian was killed and seven wounded when a car bomb went off near a police patrol.
Further north, in Mosul, Iraq's third city where ethnic tensions between Arabs and Kurds are also high, a roadside bomb killed a policeman when it detonated close to his patrol.
The killing of a Sunni Arab student leader, abducted after heading two demonstrations against the election results, prompted accusations against militias loyal to the ruling Shia alliance and their Kurdish allies in the interim government.
Anger flared around the university campus in Mosul after the body of Qusay Salah al-Din, president of the student union, was identified. He had been kidnapped on Thursday with one of his friends. The two bodies were found on Saturday, handcuffed and shot in the head.
No group claimed responsibility for the killing.
Official election results are not expected before January, but preliminary reports suggest that Shia-based religious parties will dominate parliament, heightening fears of sectarian division.
"Without the Sunni parties there will be no consensus government"
Sunni and secular parties were reported to have demanded a re-run of the 15 December election and threatened to boycott parliament.
But one of the main prominent Sunni Arab groups, the Iraqi Concord Front, denied reports that it had decided to boycott the political process.
Adnan al-Dulaimi, a Sunni politician, speaking to Aljazeera by telephone from Amman on Sunday, said groups that had rejected the outcome of recent elections in Iraq had met in Amman to demand the annulment of election results in a number of cities.
But he added: "We have not decided to suspend participation in the political process."
Aljazeera's correspondent in Jordan spoke to another representative, Shaikh Khalaf al-Alayaan, who however said opposition groups had agreed not to participate in any government, even a government of national unity.
The correspondent said delegates of the political parties held a meeting at the resident of the leader of the secular Iraqi List, Iyad Allawi, and decided they would boycott the political process as long as the matter of their representation in the new parliament was not settled.
Meanwhile, Jalal Talabani, the Iraqi president, urged Sunnis to join a consensus government.
Speaking in Sulemaniya in Iraqi Kurdistan, in between talks with Zalmay Khalizad, the US ambassador, Talabani said: "Without Sunni parties there will be no consensus government ... without consensus government there will be no unity, there will be no peace."