Clashes were reported on Tuesday in the flashpoint town of Cizre, in Sirnak Province, where demonstrations were held over curfews and restrictions on freedom of movement imposed by the Turkish government.
The sound of heavy gunfire and sporadic shelling echoed in the streets as police launched successive raids on the alleged positions of members of the Kurdistan Workers' Party (PKK).
The Turkish military announced in a statement that at least 14 PKK members were killed in the southeast, saying that 12 of those were "neutralized" during a counter-terrorism operation in Cizre.
The statement said that a Turkish soldier and two PKK terrorists were also killed in an operation in Olek village in the southeastern province of Bitlis, according to the state-run Anadolu agency.
Heavy clashes were also reported in Silopi in Sirnak, where Turkish officials said PKK militants reportedly opened fire on civilians who tried to escape from the city.
Police also used water cannon and tear gas to disperse protesters in the city of Diyarbakir, Press TV reported.
Ankara has been engaged in a large-scale campaign against the PKK in its southern border region in the recent past. The Turkish military has also been conducting offensives against the positions of the PKK in northern Iraq.