Eight Turkish soldiers have been killed in a bomb attack in the south-eastern province of Siirt, the army says.
The bomb exploded on a highway as a military vehicle was passing. Seven more soldiers were wounded.
No-one said they carried out the attack, but the army blamed it on Kurdish PKK militants.
Four troops died in gun battles with the PKK in Diyarbakir province. The attacks come amid a wave of violence after a two-year truce failed.
Separately, two people have been arrested after gunfire was heard outside Istanbul’s iconic Dolmabahce Palace, which houses offices of the prime minister.
One policeman was slightly injured in the attack and a third suspect is being sought, the Turkish Anadolu news agency reported.
A statement from the Istanbul governor’s office said the attackers were from a “terrorist group” and that they had previously carried out an attack on the Istanbul HQ of the ruling AK party on 8 August.
Prime Minister Ahmet Davutoglu was in Ankara at the time of the attack.
The palace, in the Besiktas district on the European side of Istanbul, was the main administrative centre of the Ottoman Empire for many years in the 19th and early 20th centuries.
The founder of modern Turkey, Mustapha Kemal Ataturk, died there in 1938, and the palace is now a major tourist attraction.
A man suspected of belonging to the banned leftist group DHKP-C was arrested in January after attacking guards outside the palace.
Turkey has been on high alert since launching a two-pronged air campaign against the Islamic State group in Syria and PKK bases in northern Iraq last month.