Turkey MPs held in probe after failing to answer summons
As part of the investigation, Demirtas was detained at his Diyarbakir residence on the same grounds.
The two politicians vowed in June they would not cooperate with officials on the probe and would refuse to testify.
Yuksekdag and Demirtas face prosecution under anti-terrorism laws after their parliamentary immunity was lifted earlier this year, along with other lawmakers from Turkey’s main political parties.
The two detentions are part of a broader operation against HDP lawmakers by prosecutors in Diyarbakir, Hakkari, Van, Sirnak and Bingol provinces, located in the southeastern and eastern regions, security sources tell Anadolu Agency.
They were the only parliamentary group who refused to testify in investigations against them after their immunity was lifted.