By Seyhmus Cakan
DIYARBAKIR, Turkey (Reuters) - Turkish military helicopters killed 12 Kurdish militants in strikes near the southeastern border with Syria on Wednesday, security sources said, in a conflict becoming increasingly intertwined with developments in Turkey's war-torn neighbor.
The Cobra attack helicopters launched the assault at around 6 a.m. (0400 GMT) as a group of Kurdistan Workers Party (PKK) fighters traveled through a mountainous area near the Idil district of Turkey's Sirnak province, the sources said.
Parts of Idil were placed under 24-hour curfew last week as the security forces carried out an operation against the militants. That was part of a wider military campaign which began last December in towns in the mostly Kurdish southeast following the collapse in July of a ceasefire with the PKK.
Late on Wednesday, Turkish warplanes carried out an air bombardment on PKK camps in Qandil, the group's center in northern Iraq, sources said, hitting ammunition depots, shelters and logistical centers.
The violence in Turkey's southeast is at its worst since the 1990s, turning parts of the region into a war zone. PKK militants have dug trenches and erected barricades in towns and cities, and the death toll has climbed into the hundreds as the security forces try to flush them out.
It has also complicated international efforts to end the war in Syria. Ankara sees the PKK as closely linked to the Syrian Kurdish YPG militia, which has enjoyed U.S. support in the fight against Islamic State insurgents but which Ankara sees as a hostile force bent on seizing Syrian territory abutting Turkey.
Prime Minister Ahmet Davutoglu has blamed a member of the YPG, working with Kurdish militants inside Turkey, for a suicide bombing that killed 29 people in the capital Ankara last week, most of them soldiers.
The Turkish armed forces shelled YPG positions in northern Syria in the days after the attack and bombed PKK camps in northern Iraq, as the government vowed that those responsible would pay the price. Clashes inside Turkey have also continued.
On Tuesday, security forces killed six PKK militants in Idil and two others in the Sur district of the region's largest city Diyarbakir, the armed forces said in a statement. One soldier died of his wounds after coming under attack from PKK fighters in Sur on Wednesday, it said. Another was lightly wounded.
The statement also said security forces had detained four members of the PKK and PYD, the political arm of the Syrian YPG, on Tuesday in the Akcakale district of Sanliurfa province, two of whom had sought to cross the border from Syria illegally.
The PKK is deemed a terrorist group by Turkey, the United States and European Union. It launched its insurgency in 1984.
(Additional reporting by Humeyra Pamuk; Writing by Nick Tattersall; Editing by Daren Butler/Mark Heinrich)