Turkey's government is holding an urgent meeting to discuss how to respond to the killing of 13 soldiers by Kurdish separatists on Sunday.
The PKK is fighting for autonomy in south-eastern Turkey
Prime Minister Recep Tayyip Erdogan said before the meeting the "struggle against terrorism" would change direction, but did not elaborate.
The Turkish soldiers were ambushed by the PKK rebels in the Sirnak province close to the Iraqi border, Ankara said.
Turkey says about 3,000 PKK fighters are based in Kurdish-run northern Iraq.
It has repeatedly called on the US and Iraq to take action against the PKK (the Kurdistan Workers' Party), warning Baghdad that Turkish troops could launch a cross-border raid.
"Thirteen members of our armed forces were killed in an attack... carried out by terrorists on one of our units serving in the Sirnak region," the Turkish army said in a statement on Sunday.
It was one of the heaviest losses the military had sustained in clashes with the group.
PKK spokesman Abdul Rahman al-Chadarchi later confirmed the attack, saying the rebels sustained no casualties.
In response, the Turkish military shelled the border area in an attempt to prevent the fighters from fleeing to northern Iraq.
The BBC's Sarah Rainsford says there have been almost constant clashes between Turkish forces and the PKK since thousands of troops were deployed in the border region earlier this year.
She says Sunday's ambush will increase military pressure on the Turkish government to send troops across the border.
Last month, Iraq denied Turkey permission to pursue armed separatists onto Iraqi territory.
Instead Iraq and Turkey signed a wide-ranging security agreement, pledging to prevent finance, logistical support and propaganda for the PKK.
The PKK has been fighting for autonomy in south-eastern Turkey since 1984 and more than 30,000 people have been killed in the conflict.
The PKK has been labelled a terrorist organisation by Turkey, the US and the EU.