Turkish prosecutors have begun investigating a proclamation of “democratic autonomy” by a Kurdish organization in southeastern Turkey.

The statement was issued in the southeastern province of Diyarbakir Thursday by the Democratic Society Congress — an umbrella group of pro-Kurdish politicians and activists.

Prosecutors are reportedly considering filing charges against some of its leaders.

The proclamation came amid increased tensions between Turkey and its Kurdish minority after a clash Thursday that killed 13 soldiers and seven members of the outlawed Kurdistan Workers’ Party.  There has also been a standoff in parliament between the ruling party and Kurdish lawmakers.

The United States denounced Thursday’s attack, which took place as Secretary of State Hillary Clinton traveled to Turkey for international talks on Libya.

The latest events sparked anti-Kurdish protests and an overnight firebomb attack on an office of a Kurdish party in the capital, Ankara.

The Kurdistan Workers’ Party has been fighting for an ethnic homeland in southeastern Turkey since 1984.  That fighting between Turkish forces and the rebels has killed about 40,000 people.

The 36 Kurdish lawmakers elected to parliament have refused to take the oath of office to protest court rulings that leave several of their colleagues in prison, unable to take their seats.