Six Turkish soldiers, two state militiamen and 11 Kurdish militants have been killed as the rebels attacked military outposts in southeast Turkey.
Turkish Prime Minister Tayyip Erdogan accused unnamed foreign countries of backing the fighters who attacked at least three military bases.
Sixteen other soldiers and six civilians were wounded in the overnight attacks on the bases near the town of Cukurca in Hakkari province, which borders Iraq, sources said.
Mr Erdogan called the attack "dastardly".
"Turkey has the strength to put enemy nations and circles who hold the strings of the terrorist organisation in their place," he said in statement.
Clashes between the army and the Kurdistan Workers Party (PKK) have intensified in recent weeks in a conflict that has lasted 28 years and killed 40,000 people, mainly Kurds.
In a separate operation, air bombardments of PKK positions in the nearby Semdinli region over the last two weeks has forced some villagers from their home, witnesses said.
Turkey's army killed 115 members of the PKK, in battles in southeast Turkey since July 23 and fighting is continuing, Interior Minister Idris Sahin said.
Reuters