At least 12 people were killed and 18 others wounded in separate violent attacks across Iraq on Friday, police said.

Two people were killed and six others wounded when a roadside bomb went off near a market in Baghdad's northwestern neighborhood of Shuala, a police source told Xinhua, adding that several shops were damaged in the blast.

Two civilians were injured when another roadside bomb exploded in Abutsheer of south Baghdad, he said.

A suicide car bomber targeted a checkpoint on the main road between Ana and Rawa areas in Iraq's western Anbar province, killing two soldiers and one policeman and injuring six others, a local police source said.

Two children were killed and four others were injured when a mortar shell fell on a square in downtown Ramadi, the capital of Anbar province which is some 110 km west of Baghdad, the source said.

Unidentified gunmen stopped a civilian car and shot dead three soldiers wearing civilian clothes west of Tikrit, 170 km north of Baghdad, the police source said.

Two policemen were killed when gunman throw a hand grenade at their patrol north of Baiji, some 200 km north of Baghdad, the source said.

Iraq is witnessing its worst violence in recent years. According to the UN Assistance Mission for Iraq, a total of 8,868 Iraqis, including 7,818 civilians and police personnel, were killed in 2013, the highest annual death toll in years.