Five Turkish soldiers have been killed in an attack by suspected Kurdish rebels, officials say.
At least six others were reportedly wounded in the attack, in Turkey's south-eastern Hakkari province.
It is the most serious loss of life for the Turkish army since six soldiers died in a bomb attack in early July.
Kurdish rebels have stepped up their campaign of attacks on civilian and army targets in the past few months.
Long-range weapons
The attack happened in the early hours of Friday near the town of Semdinli, which is close to the country's borders with Iran and Iraq.
Private CNN-Turk television said a powerful explosion was set off before rebels opened fire on the soldiers. The rebels made their escape by fleeing into the mountains.
A number of the injured soldiers were reportedly airlifted by helicopter to a military hospital in the main provincial town of Hakkari.
Security forces have launched an operation to catch the rebels.
The attack came only hours after Kurdish rebels freed a Turkish soldier they had held for more than three weeks.
The separatist Kurdistan Workers' Party, known as the PKK, has been fighting the government since 1984 in a campaign to create a Kurdish homeland in the south-east.
More than 37,000 people have been killed since then.
The rebels declared a unilateral truce in 1999, but ended it in 2004, saying Turkey had not done enough to meet their demands.