Lawyer Firat Epozdemir, board member of Istanbul Bar Association, was arrested on Saturday on charges of "membership in an armed terror group" and "disseminating terror propaganda" by an Istanbul court, the private NTV broadcaster reported.

Epozdemir was detained at Istanbul airport on Thursday as part of an investigation.

Istanbul prosecutors accuse Epozdemir of joining in terror group's WhatsApp group in 2015 at the peak of the clashes between Kurdish militants and Turkish security forces in the Kurdish majority southeast.

Ankara and its Western allies have branded the PKK a terror organisation over its bloody war that began in 1984 and has since left more than 40,000 people dead.

The government has been criticised for reducing the Kurdish question to little more than a "terror" issue without accounting for the demands of a community that makes up 15 to 20 percent of Turkey's 85 million citizens.