Turkey's constitutional court has banned the country's main pro-Kurdish party for having links to armed separatist fighters.
The court voted on Friday to shut down the Democratic Society Party (DTP) and banned dozens of members from joining other political parties for five years.
It also expelled two of the party's politicians, including Ahmet Turk, the DTP leader, from parliament.
The court found the party guilty of co-operating with the Kurdistan Workers Party (PKK), which has been fighting for autonomy in Turkey's mainly Kurdish southeast in a conflict that has lasted years and claimed lives.
The ruling is likely to hamper Turkey's efforts to join the European Union, which had warned Ankara that banning the party would violate Kurdish rights.
The ruling comes after weeks of clashes between police and protesters angry at the the prison treatment of Abdullah Ocalan, the founder of the PKK.
Earlier this week a protester was shot dead as pro-Kurdish protesters marched in the city of Diyarbakir.
Anita McNaught, Al Jazeera's correspondent in Turkey, said there are fears the ruling will lead to more violence.
The DTP was founded in 2005 as a successor to several Kurdish parties that were forced to wind up for collaborating with the PKK.
The PKK is listed as a terrorist group by Turkey and much of the international community.
Cengiz Aktar, a columnist with the Turkish Hurriyet Daily News, said there are "some links" between the DTP and the PKK but criticised Turkey for making party closures "a habit".
"The links apparently are there, according to the constitutional court. But in modern democracy, party closures are very seldom," he told Al Jazeera.
"This one really comes at a very unfortunate moment when the country was making a very important opening towards its Kurdish minority
"It's a totally new era and suddenly comes this unacceptable decision that may overturn the whole democratisation process and bring the country to the verge of chaos."