The PKK's three-decades-old insurgency flared up again in July after the collapse of a two-year ceasefire, leaving a peace process in tatters and plunging the mainly Kurdish southeast back into conflict.
The towns of Cizre and Silopi, near the Syrian and Iraqi borders in the province of Sirnak, were placed under curfew on Monday as Turkey launched anti-PKK operations in which Turkish media says 10,000 police and troops are taking part, Reuters reported.
Prime Minister Ahmet Davutoglu pledged on Tuesday to prevent the PKK "spreading the fire" from Syria and Iraq to Turkey by imposing control in towns, like the army has done in mountainous areas where the militants were active in the past.
The co-leader of Turkey's parliamentary pro-Kurdish party has said 200,000 people have been displaced in the southeast in recent months as a result of conflict hitting areas under curfew, accusing the state of conducting a war against Kurds.