Attacks in Iraq's confessionally mixed Diyala province, north of Baghdad, killed 18 people on Thursday, 10 of them in a market bombing in the town of Khalis, medical and security officials said.
The bloodshed came as US Vice President Joe Biden was in Iraq to usher in a new phase in relations between Washington and Baghdad nearly nine years after the US-led invasion.
"We counted 10 bodies and at least 20 wounded in the explosion of a car bomb parked near a vegetable market in Khalis," an Iraqi army colonel said, speaking on condition of anonymity.
The casualty toll was confirmed by a medic at the main hospital in the Diyala provincial capital, Baquba.
"We received 10 bodies and admitted 25 wounded. Two policemen were among them," said Dr Firaz al-Dulaimi.
In a separate attack, gunmen using silencers raided three homes in the Diyala village of Jil al-Said, south of Baquba, killing eight people, among them two commanders of an anti-Qaeda militia and members of their families, the army colonel said.
They killed five people in one house, three in a second and wounded five in the third, the officer said.
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The Sahwa militia are made up of Sunni Arab tribesmen and former insurgents who joined forces with the US military against Al-Qaeda from late 2006, helping turn the tide against the jihadists.
Amir al-Khuzai, adviser to Prime Minister Nuri al-Maliki for reconciliation affairs, said late last month that the Sahwa once numbered about 87,000, but that more than 40,000 of them are still awaiting promised public sector jobs.
In the capital, a roadside bomb in the mainly Sunni Arab neighbourhood of Adhamiyah wounded five people, an interior ministry official said.
And in Taji, 25 kilometres (15 miles) north of Baghdad, a bomb targeting a police patrol wounded four people -- two police and two civilians -- the official added.
A suicide bombing killed 12 people in the same town on Monday.
The violence came just weeks before US troops are due to a complete a withdrawal from Iraq that has raised concerns about the ability of Iraqi forces to maintain security.
The end-of-year pullout brings to a close an almost nine-year war that has left thousands of American soldiers and tens of thousands of Iraqis dead, and cost hundreds of billions of dollars.
Violence has declined nationwide since its peak in 2006 and 2007, but attacks remain common. A total of 258 people were killed in October, according to official figures.