Protesters gathered in a central square in Diyarbakir, chanting slogans in Kurdish, including "Serok Apo" (Leader Apo), in a show of support for the 77-year-old, held on Imrali prison island since 1999.

The rally comes after the PKK last year formally renounced its armed struggle against the Turkish state, ending a conflict spanning four decades that has claimed at least 50,000 lives.

Following Ocalan's call for the group to lay down its weapons, the PKK announced its dissolution, staged a symbolic arms-burning ceremony, and withdrew its fighters from Turkish territory.

Addressing the crowd in Diyarbakir, Veysi Aktas, a former inmate once held with Ocalan on Imrali, warned that lasting peace would not be possible while the leader remained in isolation.

"There can be no peace through isolation," he said.

"Through isolation, the leadership is being distanced from the people. Peace means recognition of the people, respect for identity, and respect for the will of the people".

Despite repeated calls from supporters and pro-Kurdish politicians to ease Ocalan's detention conditions, his situation remains largely unchanged.

He has however recently been granted increased access to family members, lawyers and a small number of lawmakers from the pro-Kurdish DEM party involved in ongoing peace efforts.