Turkey's parliament on Tuesday stripped HDP co-chair Figen Yuksekdag off her Member of Parliament status.
Yuksekdag has been in jail for the past three months on terror-related charges for having alleged links to the PKK terrorist organisation, and of furthering the group’s violent agenda.
The party and Yuksekdag have denied any links to the group.
Last May, Turkey’s parliament approved the lifting of immunity from parliamentarians, after which a number of MPs from various parties were summoned to give court testimony.
Thirteen HDP members, including Yuksekdag and the party's other co-chair Selahattin Demirtas, were arrested after they refused to testify in court when summoned.
Demirtas was also sentenced to five months in prison on Tuesday after being found guilty of "insulting the Turkish people, the Republic of Turkey and state institutions."
According to the constitution, an MP cannot be tried without permission from parliament.
TRT World's Hasan Abdullah has more from Ankara.