Six policemen and four anti- Qaida militiamen were killed by gunmen in two incidents in Iraq's Salahudin province, a provincial police source said on Sunday.

In one of the attacks, gunmen stormed a police checkpoint before dawn and shot dead six policemen outside a village near the city of Tuz-Khurmato, some 90 km east of the provincial capital city of Tikrit, the source told Xinhua on condition of anonymity.

Late on Saturday night, police found the bodies of a leader of government-backed Sahwa paramilitary group, his two sons and nephew, who were kidnapped by gunmen three days ago from their home near Tikrit, some 170 km north of the Iraqi capital of Baghdad, the source said.

The Sahwa militia, also known as the Awakening Council or the Sons of Iraq, consists of armed groups, including some powerful anti-US Sunni insurgent groups, who turned their rifles against the al-Qaida network after the latter exercised indiscriminate killings against both Shiite and Sunni Muslim communities.

Salahudin province is a Sunni dominated province, its capital Tikrit is the hometown of former president Saddam Hussein.

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 civilian police personnel, were killed in 2013, the highest annual death toll in years.