Turkey's prime minister has vowed that Kurdish rebels will pay a "heavy price" after launching an ambush that killed 13 Turkish soldiers.
Soldiers, air force bombers and helicopter gunships began a major offensive in south-eastern Turkey on Friday, the Associated Press reported.
It followed the ambush on Thursday in which seven rebels were also killed - the deadliest clash in three years.
Meanwhile, a Kurdish umbrella group declared "democratic autonomy".
"As the Kurdish people we declare democratic autonomy, remaining bound to the national unity of the peoples of Turkey," read Aysel Tugluk, deputy chairwoman of the Democratic Society Congress (DTK) on Thursday, at about the same time that the ambush was taking place.
The DTK describes itself as a local grouping of Kurds in eastern Turkey, comprising intellectuals, representatives from civil society organisations and pro-Kurdish politicians.
Commentators say its "democratic autonomy" idea has not been clearly defined, but it angered the government.
Prosecutors opened an investigation into the declaration, and could press criminal charges against some of the 850 delegates who took part in the DTK event.
Turkish Prime Minister Recep Tayyip Erdogan dismissed the declaration as a "self-styled thesis", and drew a clear link between the PKK rebel group and Kurdish political activists.
"I'm openly telling the terrorist organisation and its extensions that they should never expect any goodwill on our part in the face of such ill-intentioned actions," he said, referring to Thursday's ambush.
"If they want peace, there is one thing to do: the terrorist organisation must lay down arms," he said, referring to the PKK.
A tentative Kurdish peace process begun under Mr Erdogan several years ago failed to get off the ground, although Kurds have been granted some improved cultural rights.
The main Kurdish political party, the DTP, is currently boycotting parliament, demanding the release from prison of several of its members who won election to parliament last month.
The PKK's armed campaign for Kurdish autonomy dates back to 1984, since when more than 40,000 people have been killed.