European Commission President Jean-Claude Juncker has called on Kosovo to ratify a border demarcation agreement with Montenegro and seek better ties with Serbia.
Juncker, together with EU foreign policy chief Federica Mogherini and Enlargement Commissioner Johannes Hahn, continued his tour of the six Balkan countries that remain outside the European Union with a stop in Kosovo on February 28.
It was the first such visit by a head of the EU executive to the young independent state.
The EU has said the border treaty is a precondition for Kosovo's citizens to travel freely within its Schengen visa-free travel zone.
Opposition parties claim that Kosovo will lose territory with the 2015 agreement, although that has been denied by the previous government and international experts.
Montenegro, which has approved the deal, recognizes Kosovo's 2008 independence from Serbia, which Belgrade rejects.
Juncker, speaking in the capital, Pristina, also said that "ties between Kosovo and Serbia are fundamental" in their path toward Europe.
Earlier on February 28, Juncker urged Bosnia-Herzegovina's leaders to overcome their differences if they want the country to join the European Union.
"Nationalism is a poison and it is contrary to European values," Juncker told Bosnia's parliament in Sarajevo.
Based on the 1995 pact that ended Bosnia's three-year civil war, the country consists of two highly autonomous entities, the Muslim-Croat Federation and the Serb-run Republika Srpska.
Bosnia applied for EU membership 18 months ago, but the reform process has stalled amid political quarrels among the country’s leaders.
"It requires joint efforts for a state to become a member," Juncker told lawmakers. "When there are differences, it leads to paralysis, it leads to delays."
Juncker received from Bosnian officials a questionnaire on the country's readiness to join the bloc.
"I cannot promise you a date for when your country becomes a candidate," he told the Bosnian political establishment gathered for the handover ceremony. "The essence is more important than the date."
It took more than a year for Bosnia’s multiple administrations to agree responses to more than 3,000 questions relating to the compatibility of Bosnia's economic, legal, and social systems with EU standards.
Addressing Bosnia’s parliament, Juncker called on politicians to agree on changes to the election law, to tackle organized crime and corruption, and to resolve its territorial disputes.
Bosnian officials say they hope their country will be granted the status of an EU candidate later this year.