Brussels, Aug 18 : Josep Borrell, the European Union's (EU) foreign policy chief, on Thursday started high-level crisis talks between Kosovo and Serbia in Brussels, urging both sides to show flexibility. "Recent tensions in the north of Kosovo have demonstrated yet again that it is time to move forward towards full normalisation," Borell said in a tweet. Hoping for progress, Borrell called on both Serbian President Aleksandar Vucic and Prime Minister of Kosovo, Albin Kurti, "to be open and flexible to find common ground". The two Balkan leaders arrived for the EU-mediated talks after separately meeting with NATO Secretary General Jens Stoltenberg on Wednesday to discuss recent tensions. The NATO chief hosted talks after a dispute over car licence plates and identity documents in late July resulted in barricades and shots fired close to the Kosovo-Serbia border. KFOR, NATO's peacekeeping mission in Kosovo, numbering around 4,000 troops, said in response that it was monitoring the situation closely and is prepared to intervene "if stability is jeopardized". While welcoming the now-improved situation, Stoltenberg repeated that KFOR "will take any measure that is necessary to ensure a safe and secure environment and freedom of movement for all the people of Kosovo." Kosovo, which is predominantly inhabited by ethnic Albanians, broke away from Serbia in 1999 and declared independence in 2008. Serbia has not recognised Kosovo's independence and continues to lay claim to the territory. Most NATO and EU countries recognize Kosovo as a separate state. /IANS