A top Kosovo Serb politician detained over suspected war crimes against ethnic Albanians has been hospitalised after his health deteriorated from a hunger strike, a medical official said Saturday.

Oliver Ivanovic, who is being tried by an EU tribunal in northern Kosovo for war crimes allegedly committed in 1999-2000, began a hunger strike on August 7 to protest against the court's decision to extend his detention. He has been held since his arrest in January 2014, and the court has rejected his request for release several times.

"His life is not endangered at this moment, but his health has deteriorated over the hunger strike and he is refusing to receive" treatment, Milan Jakovljevic, head of the medical team that admitted Ivanovic to hospital, told reporters.

"It is necessary to keep him in the hospital" for the time being, he said.

Last week the EU court rejected Ivanovic's latest request for a provisional release, despite the Serbian government's guarantees that Ivanovic would be reachable and stand trial.

Serbian Prime Minister Aleksandar Vucic called the court's decision "senseless" and it was "aimed at further humiliation of Kosovo Serbs".

The 62-year-old Ivanovic, who is considered a political moderate, is the first senior Kosovo Serb official to be charged and tried by the European Union Rule of Law Mission (EULEX) on suspicion of war crimes against ethnic Albanians.

Ivanovic, a former Serbian secretary for Kosovo, pleaded not guilty in August 2014 at the start of his trial, which is due to resume on September 10.

After the 1998-1999 Kosovo war, Ivanovic became a key interlocutor with NATO, the UN and later the EU and was seen as backing dialogue with the Kosovo Albanian community.

However, he was also among the organisers of a now-disbanded Kosovo Serb group of vigilantes known as "Bridgewatchers", whose members were suspected of taking part in violence against ethnic Albanians.

Some 120,000 ethnic Serbs live in Kosovo, which declared independence from Serbia in 2008 and has about 1.8 million inhabitants, most of them ethnic Albanians.

Kosovo has been recognised by more than 100 countries, including the United States and a majority of the EU states.