TIKRIT, Iraq, June 25 (Xinhua) -- A policeman was killed and six security members wounded after the extremist Islamic State (IS) group kidnapped six civilians from a village in Iraq's central province of Salahudin, a provincial security source said Monday.

Before Sunday midnight, IS militants in two vehicles broke into the houses of a village near the town of Dour, some 150 km north of Iraq's capital Baghdad, and kidnapped six civilians before they apparently moved to the IS hotbed of Mteibijah, a rugged area in the eastern part of the province, Lt. Col. Mahmoud Jasim from Salahudin Operations Command told Xinhua.

After midnight, IS militants attacked outposts of police and paramilitary Sunni tribal fighters at the edges of Mteibijah area, sparking heavy clashes that only ended after interference of two helicopter gunships, Jasim said.

The clashes resulted in the killing of a policeman and the wounding of six security members, while there are no immediate reports about casualties among the attackers, Jasim added.

The Iraqi security forces repeatedly tried to retake control of Mteibijah, but the vast rugged land and mountains have made it difficult for them to dislodge the extremist militants from the region.

Hundreds of IS militants earlier fled their former bases in the key cities of Salahudin, including the provincial capital Tikrit, some 170 km north of Baghdad, after the Iraqi forces cleared these areas during major anti-IS offensives.

Late in 2017, Iraqi Prime Minister Haider al-Abadi, also the commander-in-chief of Iraqi forces, officially declared full liberation of Iraq from IS militants after Iraqi forces recaptured all the areas once seized by the extremist group.

However, some IS remnants have since melted in urban areas or fled to deserts and rugged areas in the country, carrying out attacks from time to time against security forces and civilians.