Turkish Prime Minister Ahmet Davutoglu said on Monday it would not be appropriate to have discussions with the pro-Kurdish Peoples' Democratic Party (HDP) over a new constitution because of its "insulting" comments.
Davutoglu did not give examples of the HDP's purported comments, but he and the HDP's leadership have long been at odds over policy in the mainly Kurdish southeast. Violence in the southeast has flared up since peace talks collapsed in July.
The HDP accuses the government of killing civilians, something it denies. In turn, the government says the HDP supports terrorism. The HDP denies that.
"If they think I will tolerate their insults they are mistaken," Davutoglu said at a news conference in Istanbul before departing for a trip to Serbia. "Either they will be serious and our door will be open for them or we will bring them into line."
Following on from the government's sweeping election victory in November, it is now starting negotiations towards a new constitution aimed at creating a presidential system. Davutoglu said he would hold constitutional talks with the other opposition parties.
Over the last two weeks, fighting has been intense in two towns in the southeastern Sirnak province, where the military says more than 200 Kurdish militants have been killed. Kurdish groups meeting in the southeast on Sunday called for self-rule, comments that are likely to infuriate Ankara, which opposes a separate Kurdish state.
Turkey's Kurdish issue has also been complicated by US support for Kurdish forces in Syria. A US-backed alliance of Syrian Kurds and Arab rebel groups captured a dam from Islamic State on Saturday, a military advance likely to also worry Ankara.
Russia is now also lending vocal support to Syrian Kurds.
Last week, while on a visit to Moscow, HDP co-head Selahattin Demirtas condemned Ankara's shooting down of a Russian warplane over Syria, comments Davutoglu described as treasonous.