At least 20 people have been killed in clashes between Turkish soldiers and Kurdish militants at three army outposts in the southeast.
Security sources said Up to 100 fighters from the Kurdistan Workers Party (PKK) launched simultaneous dawn attacks on three military observation points in Hakkari province.
Eight soldiers were killed and 16 wounded.
Twelve PKK fighters were killed in subsequent clashes.
The attacks come at a time when Turkey is making new efforts to address the grievances of the Kurdish minority to end a conflict that has scarred the region for three decades.
"We have never regarded terrorism as a matter of negotiation with anybody, and we will never do so. The only thing to do is for terrorists to lay down their arms," Prime Minister Tayyip Erdogan told reporters in Mexico, where he is attending a G20 Summit.
President Abdullah Gul condemned the violence accusing the PKK of trying to sabotage the atmosphere of trust and stability.
Several thousand PKK militants are based in mountain hideouts in northern Iraq, from where they regularly launch attacks on state targets in mainly Kurdish southeast Turkey.
In his efforts to resolve the conflict, Mr Erdogan has told parliament that Kurdish language lessons could be offered in schools.
He also suggested he was prepared to hold talks with prominent Kurdish politician Leyla Zana after she said she believed he was capable of ending the Kurdish troubles.
