French President Emmanuel Macron on Wednesday said Kosovo officials bore "responsibility" following clashes this week over local election results that left more than 80 people injured. Meanwhile NATO said it will increase its presence on the ground with 700 soldiers.
"It is very clear that Kosovar authorities bear responsibility for the current situation and there is non-compliance with an agreement that was nevertheless important, and which was secured just a couple of weeks ago," Macron told reporters in Bratislava.
Earlier this month, Kosovo's Prime Minister Albin Kurti and Serbian President Aleksandar Vucic held talks in Brussels mediated by the European Union to normalise ties between the two countries.
The clashes in north Kosovo erupted when the government in Pristina used its police force to try to install ethnic Albanian mayors in northern towns where Serbs make up the majority. Serbs had boycotted local elections.
The situation spiralled out of control after Serbs tried to force their way into a town hall in the northern town of Zvecan, but were repelled by Kosovo police firing tear gas.
The NATO-led peacekeeping force (KFOR) tried to disperse the most violent among the crowd by using shields and batons but were met by a hail of rocks, bottles and Molotov cocktails.
A total of 30 peacekeepers, 11 Italians and 19 Hungarians, were wounded in the clashes, according to KFOR.
Among the protesters, 52 were injured, three of them "seriously", while five Serbs were arrested for taking part in the clashes.
"We very clearly notified the Kosovar authorities that it was a mistake to proceed with these elections," Macron said.
The French head of state said he hoped to see the presidents of Kosovo and Serbia "together" on Thursday, on the sidelines of talks in Moldovan capital Chisinau.
NATO has decided to deploy hundreds of reinforcements to strengthen KFOR after Monday's violence.
On Tuesday, NATO Secretary General Jens Stoltenberg condemned attacks on the alliance's forces in Kosovo, saying they were "unacceptable and must stop".
"We have decided to deploy 700 more troops from the operational reserve force for Western Balkans and to put an additional battalion of reserve forces on high alertness so that they can also be deployed if needed," Stoltenberg said.
"Violence sets back Kosovo and the entire region."
US Secretary of State Anthony Blinken criticised ally Kosovo, blaming Prime Minister Albin Kurti's government for "sharply and unnecessarily escalated tensions" by installing ethnic Albanian mayors.
The United States also suspended Kosovo from an ongoing military exercise.
Kosovo declared independence from Belgrade after US-led NATO military intervention in 1999 effectively ended a bitter war between Serb forces and ethnic Albanian guerrillas.
Belgrade – along with its key allies China and Russia – still does not recognise the move, preventing Pristina from having a seat at the United Nations.
Kosovo is mainly populated by ethnic Albanians, but the Serbs who make up around six percent of the population have remained largely loyal to Belgrade, especially in the north where they are a majority.