Last year, the Kurdistan Workers' Party (PKK) formally renounced its armed struggle against the Turkish state after four decades of violence that claimed at least 50,000 lives on both sides.

In a message published by a delegation of lawmakers from the pro-Kurdish DEM party, who visited him on Imrali prison island on Sunday, Ocalan said prolonging the peace process would only "generate risk".

"It is crucial that all these efforts are grounded in a legal framework," he said, urging all actors involved to act with "responsibility".

"Remaining in a state of expectation, or prolonging that state, only generates risk. We have no time to lose."

He also referred to the skirmishes at the main opposition CHP party headquarters in Ankara on Sunday, where riot police fired tear gas days after a court dismissed its leadership.

The dramatic scuffles between police and supporters of the party's ousted leader Ozgur Ozel were the latest episode in a crackdown by President Recep Tayyip Erdogan on his political rivals.

"Is breaking into the headquarters of a political party by smashing the door with a sledgehammer something that should happen in a democracy?" Ocalan asked.

Such actions against the CHP were an "indicator of the absence of a properly functioning democracy and democratic politics", he warned.

A DEM delegation is due to visit Ozel at his offices at the Turkish parliament on Monday, from where he is now operating, the party said.