Kosovo's Constitutional Court on November 10 delayed implementation of an agreement on Serb minority rights that was brokered by the European Union.
Neighboring Serbia immediately denounced the court's ruling as a violation of the agreement mapped out in Brussels.
The agreement to grant ethnic Serb areas in Kosovo greater local powers with the possibility of funding from Belgrade is at the core of the normalization process the EU has been mediating between Serbia and its mostly Albanian former province.
But it has sparked nationalistic street protests in Pristina and rowdy scenes of opposition figures throwing tear-gas canisters in Kosovo's parliament.
Bowing to the opposition, Kosovar President Atifete Jahjaga asked the constitutional court to rule on whether the deal was acceptable under the constitution.
In its preliminary ruling, the court said it was suspending implementation until it gives a final verdict, likely in early January.
Serbian Foreign Minister Ivica Dacic said the decision was an unprecedented violation of the agreement reached in Brussels and a "threat to regional stability."
"Pristina is mocking both the international community and the European Union," Dacic said.