Kosovo's Constitutional Court has ruled that parts of a deal between Kosovo and Serbia to give more powers to ethnic Serbs in Kosovo violate the country's constitution.
In a ruling on December 23, the court said it is legal for Kosovo's minority Serbs to run their own affairs and form an association of municipalities where they are in the majority, as prescribed under the deal.
But the resulting Serbian association cannot have executive rights, which are reserved for the central government under the constitution, the court ruled.
The deal, which was brokered by the European Union in an attempt to improve relations between Serbia and Kosovo, has been vehemently rejected by opposition groups in Kosovo, sparking the worst political crisis since the Balkan state declared independence from Serbia in 2008.
Police have arrested 13 opposition party members for repeatedly releasing tear gas in parliament to protest the deal, and their supporters have repeatedly clashed with police in the capital, Pristina.
The opposition has called for a referendum or fresh elections if the government doesn't halt the deal.
Some opposition parties welcomed the court ruling on December 23, but did not say whether they would cancel a mass demonstration set for January 9.
Kosovo government sources told Reuters that as a result of the court's ruling, parts of the deal might have to be renegotiated with Serbia, and it is hard to forecast what Belgrade's reaction will be.
Kosovo's President Atifete Jahjaga, who asked the court to rule on the deal's constitutionality, has called on all political parties to respect the decision and "use this moment to restart political dialogue and restore normality to the country."