The PKK - listed as a terrorist group by Turkey and much of the world - has waged an armed campaign for self-rule in Turkey's mainly Kurdish east and southeast since 1984.
The conflict has claimed some 45,000 lives, most of them Kurds.
The group's efforts have been frustrated by a lack of support from other nations in the region, who each fear that recognising their own Kurdish communities' claims for autonomy could provoke instability.
Abdullah Gul, the Turkish president, last month said that Turkey had "an historic opportunity" to end the conflict which has hindered the country's chances of being accepted into the European Union, as well as being a source of regional tension.
The government has expanded cultural and political rights of minority Kurds under reforms aimed at improving its chance of winning entry to the EU.