At least one person has been hurt in a blast near the UN Kosovo mission in Pristina, possibly caused by a hand grenade, UN police have said.
The injured person was taken to hospital.
A UN spokeswoman said the target of the attack, which took place just outside the compound, was not clear.
Earlier this week, Kosovo's Prime Minister Ramush Haradinaj resigned after being charged with war crimes by the tribunal in The Hague.
Mr Haradinaj denies all 37 counts, ranging from murder to rape, allegedly committed by forces under his command during the 1998-99 conflict against Serb rule in Kosovo.
The Kosovo Albanian population, which considers Mr Haradinaj a hero for his role in the conflict, has staged angry protests against the indictment over the past few days.
Kosovo, which is a province of Serbia-Montenegro, has been under UN administration since 1999.