Abdul-Rahman al-Chadarchi, a spokesman for the PKK, confirmed the attack and said the Kurdish fighters had sustained no casualties.
Yilmaz Akinici, a Turkish journalist who was in the area, told Al Jazeera that one of the soldeirs killed was an officer.
He said that the incident happened very close to the Iraqi border and that the PKK fighters were thought to have escaped into northern Iraq.
"We can hear the Turkish artilery shelling the Iraqi broder," he said.
About 3,000 PKK fighters, which Turkey labels as "terrorists", are based in the mountains of northern Iraq.
Fighting between the PKK and the army has escalated recently in Turkey's mainly Kurdish southeast as the military steps up operations before winter, when harsh conditions slow down the rebels' movement.
Turkey has been pressing Iraq and the US to hit the PKK bases in northern Iraq, and has considered a unilateral military operation across the border to root out the Kurdish fighters.
On Sunday, the military designated 27 "security zones" in eastern and southeastern Turkey, where the borders with Iraq and Iran converge.
Starting on Tuesday, the zones will be in place until December 10 and the areas will be off-limits to civilians.
The military imposed similar zones earlier in June in three southeastern provinces to keep civilians away while the army battles the PKK.