No group claimed responsibility for yesterday's attacks, which targeted government officials, police patrols and members of both the Sunni and Shi'ite sects.
Seven people from the same Sunni family were killed by a bomb near their home in the town of Mussayab, south of Baghdad.
In the Shi'ite majority city of Hilla, also in the south, a parked car-bomb went off near the convoy of the governor of Babil province. The explosion missed its target but killed two other people.
"We heard the sound of a big explosion and the windows of our office shattered. We immediately lay on the ground," said 28-year-old Mohammed Ahmed, who works at a hospital in Hilla, near the site of the blast.
"After a few minutes I stood up and went to the windows to see what happened. I saw flames and people lying on the ground."
Yesterday's violence – a year since the withdrawal of US troops – followed more than a week of protests against Shi'ite Prime Minister Nuri al Maliki, involving thousands of people from the country's minority Sunni community.
Tensions between Shi'ite, Kurdish and Sunni factions in Iraq's power-sharing government rose during the past year, and militants continue to strike almost daily, with big attacks occurring monthly.
Although violence is far lower than during the sectarian slaughter of 2006-2007, about 2000 people were killed in Iraq in the 12 months following the withdrawal of US troops in December 2011. American forces had been a presence in the country since the 2003 invasion to overthrow former president Saddam Hussein.
Yesterday's attacks also included a series of blasts that killed three people in Iraq's disputed territories, over which both the central government and the autonomous Kurdish region claim jurisdiction. Two of these deaths were in the oil-producing and ethnically mixed city of Kirkuk, where a bomb exploded as police tried to defuse it.
Baghdad and Kurdistan are locked in a feud over land and oil rights, and recently deployed their armies to the territories along their contested internal boundary. Both sides are currently facing off against each other.
Efforts to ease the stand-off stalled when President Jalal Talabani, a Kurd seen as a steadying influence, suffered a stroke and was flown abroad for medical care early last month.
Iraq's Prime Minister then detained the bodyguards of his Sunni finance minister, which sparked the mass protests against Nouri al Maliki in the western province of Anbar, a Sunni stronghold on the border with Syria.
The protesters are demanding an end to what they see as the marginalisation of Iraq's Sunni minority, which dominated the country until the US-led invasion.
On Sunday, Deputy Prime Minister Saleh al Mutlaq, himself a Sunni, was forced to flee the epicentre of the protests in Anbar's city of Ramadi when demonstrators pelted him with stones and bottles.
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