Jailed Kurdish militant leader Abdullah Ocalan said on Sunday that a peace process to end three decades of conflict was still continuing with all "seriousness", but that Ankara needed to take concrete steps before parliament opens in October.

Ocalan's militant Kurdistan Workers Party (PKK) and the Ankara government began peace talks late last year to halt a conflict which has killed 40,000 people and blighted Turkey's mainly Kurdish southeast.

But a recent increase in militant activity in southeastern Turkey and frustration among Kurdish leaders over what they see as a lack of commitment by the government is fuelling fears that the process could unravel.

The PKK on Friday issued what it said was a "final warning" to Turkey to take steps to advance the process.

Ocalan, held on an island jail south of Istanbul, met on Sunday with a delegation from the pro-Kurdish opposition Peace and Democracy Party (BDP). In a statement issued by the BDP, Ocalan said the process was still on track.

"The process that we have started is continuing with its full weight, in all seriousness and depth," Ocalan said.

"However, ... the government must definitely act quickly. Near to the opening of parliament (on Oct. 1) the government is now expected to take concrete and practical steps," he said.

Ocalan said he was still hopeful over the process and that it had not reached a "deadlock".

Kurdish leaders have called on the AK Party (AKP) government to launch reforms set out under the process, but Ankara has said the Kurds need to keep their side of the bargain by speeding up the withdrawal of their fighters to northern Iraq.

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, granting full Kurdish-language education and lowering the threshold of votes that parties need to enter parliament.

As the process has faltered, there has been an increase in militant activity in mainly Kurdish southeast Turkey, which commentators say will complicate the government's task of enacting reforms without inflaming nationalist sentiment.

Prime Minister Tayyip Erdogan has invested considerable political capital in the process ahead of elections next year and is facing the biggest test of his decade in power after weeks of often violent anti-government protests.

In Sunday's statement, Ocalan also requested to be allowed to meet with the media on his prison island so he could convey better how to advance the process. Ocalan has been kept in virtual isolation since his capture by Turkish forces in 1999.

The PKK took up arms against the state in 1984 with the aim of carving out a Kurdish state, but subsequently moderated its goal to regional autonomy. Kurds represent around a fifth of Turkey's population of 76 million people.