Tele1 editor Merdan Yanardag was arrested and put in pre-trial detention on June 27 for allegedly spreading "terrorist propaganda" and "praising criminals" on air.

Yanardag questioned why Ocalan -- who headed an insurgency waged by the outlawed Kurdistan Workers' Party (PKK) until his capture by Turkish forces in 1999 -- was still being held in solitary confinement on a prison island in the Sea of Marmara.

Yanardag was detained by police within hours of making the comments. He was formally arrested and charged the following day.

The editor's lawyers and political supporters argue that prosecutors took his comments out of context.

They claim that the prosecutors' case was built on purposely misleading clips of Yanardag's television appearance that were being spread on online by pro-government "trolls".

Tele1 is a leftist opposition channel that was one four media outlets fined for their coverage of Turkey's May general election.

Turkish President Recep Tayyip Erdogan accused the opposition of backing Kurdish "terrorists" during the hard-fought campaign.

The regulator on Thursday also ordered Tele1 to pay a fine equivalent to five percent of its advertising revenues for June.

The PKK is proscribed as a terrorist organisation by Turkey and both Washington and the European Union.

Its decades-long insurgency has claimed the lives of tens of thousands of civilians and soldiers as well as Kurdish fighters.

Erdogan's government opened tentative peace talks with Ocalan's intermediaries that resulted in a 2013 truce.

The breakdown of talks in 2015 set off a new wave of violence across Turkey's predominantly Kurdish southeast.

Ocalan is a hate figure in Turkey because of the PKK's bombings and mass attacks against civilians.

But the conditions of his detention have been criticised by the European Court for Human Rights.