"Our movement is giving the ... government a final warning," read a rebel statement carried by Firat news agency, which is close to the rebels. "In the event that concrete steps are not taken at the shortest time, the process will not advance and the government will be held responsible."
The statement said the government was expected to initiate reforms to boost the rights of Kurds as of June 1 and accused it of failing to carry out "its duties." It also accused the government of "sabotaging" peace efforts by refusing to allow an independent group of doctors to visit the PKK's jailed leader Abdullah Ocalan on his prison island off Istanbul and of delaying meetings between him and a group of Kurdish politicians who are involved in the peace process.
Any resumption of the fighting with the PKK would be an added headache for Erdogan. Last month, tens of thousands of people held the largest anti-government protests in decades to denounce what they said is his increasing authoritarian streak and efforts to impose conservative religious views on society.
Heightening Turkish concerns, Kurds in Syria have carved out a degree of independence in areas close to the Turkish border and this week a Kurdish group in Syria took control of a major town of Ras al-Ayn, after fierce battles with rebels from radical Islamic groups. The Kurdish group, the Democratic Union Party, or PYD is seen as an offshoot of the PKK.
Stray bullets from the fighting hit a Turkish border town, killing one teenager and injuring at least four other people. The Turkish military said it had retaliated on Wednesday and Firat said the military had targeted Syrian Kurdish positions in Ras al-Ayn.
"The Turkish armed forces have, in line with their rules of engagement, given the necessary response to the fire," Davutoglu said during a joint news conference with his Greek counterpart. "As of now, the most effective measure will be taken against any kind of threat against our border security whichever group that threat may come from and an immediate response will be given."
The PKK statement on Friday also accused the government of supporting the radical Islamic groups against the Kurdish fighters in Syria, further impeding the peace efforts. Turkey rejects that accusation.
The PKK, which took up arms in 1984, is considered a terrorist organization by Turkey's allies in the West.
Kurds run their own autonomous region in northern Iraq. There are fears that a similar model in Syria could strengthen long-standing Kurdish demands for an independent homeland for the more than 25 million Kurds in parts of Turkey, Iran, Syria and Iraq.