Kurdish fighters have attacked police and military posts in a town near the Iraqi border with long-range weapons and rocket launchers, killing 10 security force members, according to a Turkish official.
The attack on security forces in the town of Beytussebap, in Sirnak province, late on Sunday set off clashes that also killed several Kurdish fighters, Vahdettin Ozkan, governor for the southeastern Sirnak province, told the state-run Anadolu Agency on Monday.
He did not say how many fighters were killed.
Seven soldiers were wounded in the attack, Sirknak authorities said, while other local sources said about 20
members of the outlawed Kurdistan Workers' Party (PKK) were killed.
The PKK says it is fighting for self-rule in southeast Turkey in a conflict that has killed tens of thousands of people since 1984.
The fighters often stage hit-and-run attacks from bases across the border in northern Iraq.
Turkey is now concerned that the chaos in Syria is opening up a new base for the PKK, which has long been suspected of having ties to Syrian President Bashar al-Assad's regime.
There has been a surge in attacks in recent months, including a deadly bombing near the Syrian border on August 20 blamed on the fighters.
Government officials have said Turkey was investigating whether another country was involved in the attack.
The PKK is considered a terrorist organisation by the US and the European Union.