A series of attacks mostly targeting security forces, including a suicide car bomb at an army base, killed 11 people, officials said, updating a previous toll.
In the deadliest of Monday's incidents, a vehicle packed with explosives was detonated by a suicide attacker in the main northern city of Mosul, killing six soldiers and wounding seven others, according to security and medical officials.
The blast struck near a military base in the Al-Muthanna area of the city, 350 kilometres (220 miles) north of the capital.
Also in Mosul, a real estate developer, his wife, and the visiting bodyguard of a provincial council member were all stabbed to death inside the businessman's home late on Monday, officials said.
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It was not immediately clear why the group were targeted.
Even as unrest has declined nationwide from its peak in 2006 and 2007, Mosul and surrounding Nineveh province remain one of the most violent regions of the country on a per capita basis, according to the Iraq Body Count watchdog.
Also on Monday, a roadside bomb in the northern city of Kirkuk killed a policeman and wounded two others, while four separate bombings and shootings in Baghdad left one person dead and three people wounded.
No organisation immediately claimed responsibility for the attacks, but Sunni militants including Al-Qaeda's front group often target security forces and officials in a bid to destabilise the government and push the country back towards the sectarian war that blighted it from 2005 to 2008.
The violence is the latest in a wave of unrest including car bombs and suicide attacks after weeks of rallies in Sunni-majority areas calling for the ouster of Iraqi Prime Minister Nuri al-Maliki.