The European Union's rule of law mission has relaunched in Kosovo on the same four-month timetable as before, but the support of the Serbs is still critical to stamp out fuel smuggling and establish control over the state's northern border.

With the cheapest petrol in Europe, the 1,200 sq km where Serbs predominate has become a magnet for customers from Serbia. Even Kosovo Albanian motorists with "KS" licence plates are venturing north of the Ibar river to fill up, international officials say. Petrol sold in northern Kosovo last week for below €0.50 a litre, less than half the price elsewhere in Kosovo or Serbia.