Jailed Kurdistan Workers Party (PKK) leader Abdullah Ocalan and Ankara launched peace talks last October to halt a conflict which has killed 40,000 people and blighted Turkey's mainly Kurdish southeast.
Kurdish politicians have called on the AK Party (AKP) government to act quickly to launch reforms set out under the process, but Ankara has said a withdrawal of Kurdish fighters to northern Iraq launched in May is happening too slowly.
"As a movement we are warning the AKP government for the last time ... If concrete steps are not taken in the shortest time on the subjects set out by our people and the public, the process will not advance and the AKP government will be responsible," the PKK said on one of its websites.
The reforms include steps to boost the rights of the Kurdish minority, including abolishing an anti-terrorism law under which thousands have been imprisoned for links to the PKK and granting full Kurdish-language education.
The PKK repeated a call for the government to allow an independent committee of doctors to visit Ocalan on the prison island of Imrali, south of Istanbul. Ocalan is know to suffer from an eye ailment.
The PKK, designated a terrorist organisation by Turkey, the United States and European Union, also accused the government of supporting groups involved in clashes with Kurds in northern Syria. Ankara rejects those accusations.
