Six Turkish soldiers have been killed and seven injured in a rocket attack on a navy base in the country's south, state media reports.
Suspected Kurdish rebels fired on a military vehicle carrying troops in the Mediterranean port of Iskenderun.
The attack took place at about 0400 (0100 GMT). Soldiers at the base fired at the attackers but it was not clear if any were injured.
The government has recently intensified efforts to end the Kurdish insurgency.
Three Turkish soldiers were in a critical condition and were taken to a military hospital in the capital, Ankara, according to the Anatolia news agency.
Police and troop reinforcements have been sent to the area, the report said.
Five members of the Turkish security forces were killed over the weekend in clashes with Kurdish rebels in the south and east of the country.
It follows the bombing of Kurdish rebels targets in northern Iraq two weeks ago by the Turkish airforce.
Meanwhile the jailed Kurdish rebel leader, Abdullah Ocalan, has reportedly said he was abandoning efforts for dialogue with the Turkish government.
However, Ocalan - jailed since 1999 - said his decision was not a call for the Kurdistan Workers' Party (PKK) to intensify its campaign.
The PKK has been fighting for autonomy in Turkey's largely Kurdish south-east for more than two decades. Some 40,000 people have been killed.
The rebels are described as terrorists by the US and the European Union, as well as Turkey.