The Turkish military is expanding its operations against the banned Kurdistan Workers' Party (PKK) in the mostly Kurdish south-east of the country, the Dogan news agency reported on Wednesday.
A new curfew has been imposed on Idil, a district in the already hard-hit Sirnak province, the governor's office announced. Reports said there were clashes between PKK militants and state security forces in the area.
Strict, round-the-clock curfews are also in effect in several other districts in Sirnak and Diyarbakir provinces. The curfews have drawn criticism from human rights groups.
Tens of thousands of people have been displaced by fighting in the past two months.
The army, which has been using tanks and heavy weapons, says 850 PKK fighters have been killed since December, though this number cannot be verified and the PKK has confirmed a much lower figure.
Meanwhile, the pro-Kurdish Peoples' Democratic Party says 277 people have been killed and these people are assumed to be mostly civilians.
The security forces have also reported casualties but an exact total cannot be confirmed.
The PKK and the state have been fighting since 1984, in battles which have left more than 40,000 people dead. Many Kurds in Turkey have long complained of systemic discrimination.