Spokesman of the opposition Peoples' Democratic Party (HDP) Osman Baydemir has been taken into custody Friday afternoon.
A court in Diyarbakır issued an arrest warrant for the Şanlıurfa lawmaker on Tuesday after he failed to attend a trial hearing.
Baydemir is accused of insulting security forces in 2012, when he was mayor of Diyarbakır, after a protest attempt which was banned by the governor.
The spokesman has not denied the accusations, saying: "It is true that I used bad words at that time."
The charges carry a possible prison sentence of one to two years.
The Turkish government has accused the HDP of having links to the PKK, which is listed as a terrorist organization by Turkey, the U.S., and the EU.
A number of HDP deputies, including party leaders Figen Yüksekdağ and Selahattin Demirtas, were arrested last November after they failed to answer summons to testify as part of a counterterrorism investigation.
