Attacks mainly targeting members of Iraq's security forces in areas north of Baghdad killed 12 people on Wednesday, officials said.

Security forces, often plagued by shortcomings such as a lack of discipline and training, are frequently targeted by militants, as the country suffers its worst violence in years.

Gunmen attacked an army checkpoint in a village north of Baquba, killing three soldiers and wounding three more, while a bomb targeted a police major general's convoy near Tuz Khurmatu, killing two of his guards and wounding three.

Two more roadside bombs exploded in Tuz Khurmatu, killing two brothers and wounding 18 people, while a soldier was killed by a magnetic "sticky bomb" on his vehicle in Tikrit.

In Mosul, two civilians died in clashes between soldiers and gunmen who attacked their checkpoint, and two more soldiers were killed in another checkpoint attack in the northern city.

Violence in Iraq has reached a level not seen since 2008, when the country was just emerging from a period of brutal sectarian killings that left tens of thousands dead.

All of one city and parts of another to the west of Baghdad have been held by anti-government fighters for weeks.

It is the first time they have exercised such open control in major cities since the height of the insurgency that followed the 2003 US-led invasion.

Violence in Iraq has killed more than 520 people so far this month and over 1,500 since the beginning of the year, according to AFP figures based on security and medical sources.

It took just five days for this month's death toll to surpass the 246 people killed in all of February last year.