An explosive device was thrown and automatic weapons were fired at a sports hall in northern Kosovo on Sunday, some 12 hours before Serbian Prime Minister Aleksandar Vucic visited it, Serbian media reported, adding that there were no casualties.

Vucic said that the perpetrators of the blast, which occurred outside a hall at Zubin Potok at around 3:00 am (0100 GMT) as workers were setting up a stage where he made a speech later Sunday, were ethnic Serbs, the state-run news agency Tanjug reported.

The Serbian prime minister, who faces early parliamentary elections on April 24, downplayed the incident and said he was "not impressed with it."

"My response to those Serbs who wanted to give me such a 'welcome' is ... I will fight for you and your families, so you can live in your homes" in Kosovo, he said during his Serbian Progressive Paty (SNS) electoral rally at the hall, Tanjug reported.

"We want a united Serbia, Serbia against hatred."

According to media reports a vehicle parked nearby was damaged and some of the hall's windows were broken in the blast but there were no casualties.

Kosovo, a former southern province of Serbia that is populated mostly by ethnic Albanians, declared independence in 2008, although Belgrade still does not recognise its sovereignty.

Vucic occasionally visits the predominantly ethnic-Serb north of Kosovo, which lies along the border with Serbia and has tense relations with Kosovo's ethnic Albanian majority.

During his stay in northern Kosovo, Vucic also visited a mine, a Serb Orthodox monastery, the Serb-populated part of the ethnically-divided city of Kosovska Mitrovica and held the speech at Zubin Potok.

The authorities in Pristina, Kosovo's capital, did not comment the reported blast and weapons fire.

Both Belgrade and Pristina have been told to normalise ties if they want to progress towards European Union membership.