(reuters) -- They said Turkish forces launched a helicopter-backed operation in search of further Kurdistan Workers Party (PKK) militants, who sought to cross the border into Hakkari province's mountainous Semdinli district.

Two Turkish soldiers and two members of the country's state-backed village guard militia were killed in the fighting, along with four PKK members, the sources said.

The PKK launched a separatist insurgency in 1984 and more than 40,000 people have been killed in the conflict. It is designated a terrorist group by Turkey, the United States and European Union.

(File Photo: An Iraqi-Turkish border crossing point at Ibrahim Khalil, April 12, 2011 William John Gauthier, atlanticsentinel)