Istanbul — Turkey's pro-Kurdish opposition party kicked off a congress Sunday to elect new co-presidents, replacing its jailed leader.

The Peoples' Democratic Party or HDP — the second largest opposition in the Turkish parliament — is voting in Ankara amid heavy security as lawmaker Selahattin Demirtas steps down. Demirtas has been behind bars pending trial since November 2016 for alleged terror charges, accused of links to outlawed Kurdish militants. He denies any terror links.

Parliamentarians Pervin Buldan and Sezai Temelli are to take the helm from Demirtas and incumbent Serpil Kemalbey as co-leaders.

The party in May had elected Kemalbey to replace former co-leader Figen Yuksekdag, who has been stripped of her parliamentarian status and jailed on similar charges.

Seven other HDP lawmakers have been arrested under Turkey's state of emergency, which was declared following a failed coup in July 2016.

Turkey issued a detention warrant Friday against Kemalbey over her opposition to Turkey's current military offensive in northern Syria against the Syrian Kurdish People's Protection Units or YPG. Kemalbey spoke at the party's congress Sunday and has not been detained.

Turkey considers the YPG in Syria a terror organization and an extension of Kurdish insurgents fighting for autonomy for more than three decades in Turkey. Turkey launched the military operation on the Kurdish-held enclave of Afrin in northern Syria on Jan. 20, citing national security.

Since then, hundreds of people in Turkey have been detained over social media posts and protests over the military operation for alleged terror propaganda.