The number of Kurdistan Workers Party (PKK) militants to have been either killed or wounded in clashes with Turkish security forces in a day of fighting is more than 100, the military says.
Saturday (local time) was one of the highest casualty tolls in a single day of the conflict in recent years.
Turkey's largely Kurdish southeast has been rocked by waves of violence following the collapse of a ceasefire between the state and the PKK last year.
The military said in a statement that more than 100 PKK militants had been "neutralised" in clashes, without specifying how many were killed and how many wounded. It said most had been taken back to northern Iraq, where the PKK has mountain camps.
Turkey's southeast has seen heavy fighting in recent days in Hakkari province, near the border with Iraq, and in Van province, near the border with Iran.
Five Turkish security force members were killed and six more were wounded in clashes in Hakkari, security sources told Reuters. Eight more security force members were killed overnight in Van, the sources said.
More than 40,000 people, most of them Kurds, have died since autonomy-seeking PKK launched its insurgency against the Turkish state more than 30 years ago. The PKK is regarded as a terrorist organisation by Turkey, the United States and the European Union.
Turkey and its rebel allies have opened up a new line of attack in northern Syria as Turkish tanks crossed the frontier from Kilis province, making a western thrust in an operation to sweep militants from its border.
The incursion from Kilis - which has been repeatedly targeted by Islamic State rockets from inside Syria over the last year - coincided with a push elsewhere in the region by the Turkish-backed Syrian rebels, who seized several villages further east from the Sunni hardliners.
By supporting the rebels, mainly Arabs and Turkmen fighting under the loose banner of the Free Syrian Army, Turkey is hoping to push out Islamic State militants and check the advance of US-backed Syrian Kurdish fighters.
The rebels last week took the frontier town of Jarablus with Turkish support. The operation, called Euphrates Shield, is Ankara's first full-scale Syrian incursion since the start of the five-year-old war.
On Saturday the tanks crossed the border and entered the Syrian town of al-Rai to support the new offensive, a rebel spokesman and monitors said. Now under rebel control, al-Rai had previously been in the hands of Islamic State.