Violence killed seven people in Iraq on Monday, including a mother and her three children who were stabbed to death in their home and an army major killed by a bomb, officials said.

A mother, her 13-year-old boy, and girls aged five and seven were killed in the Baghdad neighbourhood of Kamaliyah after the woman's husband, who works at the ministry of health, left for his office, security and medical officials said.

It was unclear why they were targeted, an interior ministry official said, adding that the killings in the predominantly Shiite neighbourhood did not appear to have sectarian motives.

Just days earlier, a Sunni Muslim mother and her three children were shot dead in an apparent sectarian attack in a village in central Iraq, after twin bombings killed eight people, mostly Shiites.

Also in Baghdad, a magnetic "sticky bomb" attached to a car in the commercial Karrada neighbourhood in the centre of the capital killed two people and wounded five others.

The victims were all civilians, security and medical officials said.

And another sticky bomb on a car in the Latifiyah, south of Baghdad, killed Major Qais Saadun and wounded two soldiers, the interior ministry official said.

While violence is down from its peak in 2006 and 2007, attacks remain common here, killing 112 Iraqis in March, according to government figures.