Kurdish guerrillas have killed 26 Turkish soldiers in attacks on military posts in southeastern Turkey.
It is the biggest single death toll for Turkish security forces in years.
At least 18 soldiers were also wounded when militants from the Kurdistan Workers' Party (PKK) opened fire on military outposts in Cukurca and Yuksekova districts in Hakkari province on the border with Iraq.
Turkish forces said they killed 15 militants in the attack.
Turkish commandos have crossed into northern Iraq in pursuit of the attackers.
Prime Minister Tayyip Erdogan has cancelled a planned visit to Kazakhstan after the attack.
The attacks come only a day after five policemen and three civilians, including a two-year-old girl, were killed in a roadside bomb attack planted by suspected Kurdish rebels in nearby Bitlis province.
Turkish President Abdullah Gul recently visited troops in the region to boost morale in an area that has seen increased violence in recent months.
Kurdish separatists have stepped up their attacks in southeastern Turkey, killing more than 50 Turkish security personnel since July.
The Turkish military has launched retaliatory air raids on Kurdish rebel targets in northern Iraq.
