PRISTINA (Reuters) - Donald Tusk, president of the European Council, urged Kosovo on Thursday to improve relations with Serbia in order to progress towards its long-term goal of European Union membership.

FILE PHOTO: European Council President Donald Tusk attends a news conference at Euxinograd residence, near Varna, Bulgaria, March 26, 2018. REUTERS/Stoyan Nenov

Kosovo and five other Western Balkan nations seeking EU membership must all tackle corruption and organized crime, improve human rights and media freedoms and resolve any disputes with their neighbors before they can join.

Kosovo, a former Serbian province which is not recognized as an independent state by five current EU members or by Belgrade, is still far from membership talks. But it committed in 2013 along with Serbia to an EU-sponsored dialogue to improve ties.

Little progress has been made since then.

“Without a comprehensive normalization of relations with Serbia and full implementation of the agreements, I don’t see how a breakthrough in relations with the EU could be achieved,” Tusk told a joint news conference with Kosovo President Hashim Thaci.

“I know it is going to be hard but I am still a cautious optimist and after yesterday’s meeting with (Serbian President) Aleksandar Vucic and today’s meeting with your president (Thaci) I am more optimistic and less cautious.”

Tusk, a former Polish prime minister, chairs summits of the 28-nation EU.

Kosovo declared independence from Belgrade 10 years ago, almost a decade after NATO bombed Serb forces to halt the killing and expulsion of ethnic Albanians from the region during a 1998-99 counter-insurgency war.

Kosovo has been recognized by 116 countries, including 23 of the 28 EU members.

Its membership of the United Nations has been blocked by Serbia’s allies Russia and China.

Around 120,000 Serbs who live in Kosovo still consider Belgrade their capital, and they are financially supported by Serbia.