Kosovan and European Union police and customs officers were deployed at two contested border crossings with Serbia in the predominantly-Serb north of the country on Friday, an official said, amid concerns the move could provoke ethnic violence.

"Mixed teams are on the border. They were sent in by helicopters," Bajram Rexhepi, Kosovo's Interior Minister has said.

The Pristina government wants to reinstate its presence in largely lawless northern area which pledges its allegiance to Belgrade, three years after Kosovo's Albanian majority declared independence from Serbia, Reuters reported.