UN chief Ban Ki-moon has said he is concerned about continuing tensions in northern Kosovo, home to many of the territory's remaining ethnic Serbs.
Making his first visit to Kosovo since it declared independence from Serbia in 2008, he called for the situation to be eased through peaceful dialogue.
Serbs resisting rule from the ethnic Albanian majority have clashed with Nato-led peacekeepers in recent months.
Serbia continues to regard Kosovo as a breakaway province.
At issue has been control over northern border crossings used by ethnic Serbs to maintain close ties with Belgrade.
The UN oversaw the creation of local authorities in Kosovo after the war in 1999 but has since handed over much of its powers to EU bodies.
"I remain concerned about the situation in north Kosovo and the escalation of tension during the last year," Mr Ban told reporters at the airport outside the Kosovan capital, Pristina.
"It is essential that sensitive and complex issues related to the north of Kosovo be resolved through peaceful dialogue."
Kosovo is not a member of the UN as its independence has not been been recognised by Serbian ally Russia and other states, including Spain.
According to a count on pro-independence website Kosovo Thanks You, 91 of the UN's 193 member-states have to date extended recognition.
About 90% of Kosovo's population is now ethnic Albanian but some 120,000 ethnic Serbs remain, living in the northern part or in enclaves elsewhere in the territory.