The EU mission in Kosovo is having to fly staff and supplies for crossing points on the Serbian border in by helicopter.
A spokesman says it is to get round ethnic Serb roadblocks, set up to keep Kosovan officials away from two disputed border crossings.
Pristina unilaterally declared independence from Belgrade in 2008. Kosovan Prime Minister Hashim Thaci is said to have ordered the crossings be re-opened by the weekend.
Jarinje and Brnjak have been staffed by international peacekeepers since since unrest broke out in July.
The clashes erupted when Pristina sent police to the two sites, to enforce its ban on imports from Serbia. This was imposed in retaliation for an earlier Serbian ban on goods from Kosovo.
Mitrovica is the capital of this ethnically-divided region.
Serbia sees it as it’s historic heartland, and with parliamentary elections looming, Belgrade seems reluctant to give up its influence, despite an EU membership bid in the offing.