A leading Kosovo Serb politician who was twice tried for war crimes has been assassinated outside his party's headquarters.

Oliver Ivanovic's colleagues found him after he was shot dead by at least one gunman in the divided northern city of Kosovska Mitrovica, it was reported.

He was entering the building when he was ambushed.

It was reported that gunmen had shot Ivanovic up to five times just after 8am local time before fleeing.

Police have launched a manhunt for the killers.

Ivanovic had been accused of ordering the murder of nine ethnic Albanians during the Kosovo War, and organising a Kosovo Serb vigilante group called the "Bridge Watchers".

Ivanovic had been targeted for death in the past (
Image:
Bloomberg)

Ivanovic's lawyer, Nebojsa Vlajic, confirmed to Blic that the politician had been killed.

The lawyer said: "It looks like he had already died at the scene. As far as we know, he had five wounds.

"He was taken to hospital, the doctors tried to resuscitate him, but he could not be saved."

B92 reported that the politician had been shot four times in the chest.

Ivanovic, head of a Kosovo Serb political party called Freedom, Democracy, Justice, was named a suspect in a war crimes probe that began after the Kosovo War ended in 1999.

Ivanovic's retrial on war crimes charges began last year (
Image:
Bloomberg)

He was accused of ordering the murdering of nine ethnic Albanians in the town of Mitrovica on April 14, 1999, during the Nato bombing of Yugoslavia, he was allegedly the leader of a paramilitary police unit, Balkan Insight reported.

The victims were killed by the "Bridge Watchers", Serb hardliners who patrolled the main bridge dividing Mitrovica into Serb and Albanian sectors, it was reported.

In January 2016, the EU Rule of Law Mission in Kosovo sentenced Ivanovic to nine years in prison.

However, the conviction was overturned on appeal in February 2017 and a new trial began later in the year.

Ivanovic, who had gone on a hunger strike several times during his first trial, claimed the proceedings against him were a staged political process.

The former Serbian government official had been targeted for death before.

After his car was deliberately set on fire last July, he claimed he had no enemies and was not involved in "illegal business", but he "does have political opponents, b92 reported.

The married father-of-three would not name his opponents, adding: "They know, they will surely recognise themselves."

A bomb was planted under his car outside his apartment building in 2005.

His political career began during the Kosovo War in June 1999 when he was appointed president of the Serbian National Council of North Kosovo and Metohija.

The war between Serbian forces and ethnic Albanian separatists, from February 1998 to June 1999, left thousands of fighters and civilians dead, and displaced more than a million people.

Kosovo declared independence from Serbia in 2008.