Suspected Kurdish separatists killed four Turkish soldiers and wounded five more in an attack on a military convoy near the border with Iran and Iraq, a Turkish regional authority said on Saturday.
The past few months have seen some of the heaviest fighting since the outlawed Kurdistan Workers' Party (PKK) - considered a terrorist organization by Turkey, the United States and the EU - took up arms in 1984 with the aim of carving out a Kurdish state.
The governor's office in the southeastern province of Hakkari said PKK militants had used remote-controlled bombs to attack the convoy in Hakkari's Cukurca district.
Turkish armed forces have killed more than 80 Kurdish militants over the past week in a major offensive involving several thousand ground troops and air strikes on PKK bases, some of them across the border in northern Iraq.
The conflict has killed more than 40,000 people, hampered economic development in one of Turkey's poorest corners, and added to instability in an already fragile region bordering Iran, Iraq and Syria.
More than 700 people have been killed since parliamentary elections in June last year, making this the deadliest period since the capture of PKK leader Abdullah Ocalan in 1999, the International Crisis Group (ICG) said in a report this month.