BELGRADE (Reuters) - A Serbian ultra-nationalist who is resisting an order from a U.N. court to return to The Hague to hear the verdict in his war crimes trial flaunted his defiance on Thursday by holding up burning EU and NATO flags outside a Belgrade court.

Serbian ultra-nationalist leader Vojislav Seselj, surrounded by his Radical Party supporters, burns a NATO flag during a protest in front of the Special Court building in Belgrade, March 10, 2016. REUTERS/Stringer

Vojislav Seselj, who has liver cancer, was freed on compassionate grounds in November 2014 by the United Nations court trying war crimes in the former Yugoslavia.

But four months later judges in The Hague ordered him to return, saying he had broken the terms of his release by telling supporters he would never go back to The Hague.

Seselj repeated on Thursday that he would not voluntarily return to The Hague, which has set March 31 as the date for giving its verdict on his alleged role in fomenting the Balkan wars of the 1990s, when he headed the biggest party in Serbia’s parliament and led paramilitaries in wars in Croatia and Bosnia.

“I will not go voluntarily, but I will use every opportunity to inflict expert, professional, political and moral damage on the Hague tribunal,” Seselj, 61, told several dozen cheering supporters of his Radical Party in front of the High Court in Belgrade.

Seselj’s performance came after Serbia’s High Court, which also tries war crimes, cancelled a hearing on his extradition to the Hague tribunal for procedural reasons.

“It burns well,” Seselj said, holding up an European Union flag which had been set alight by a supporter. A NATO flag received the same treatment.

Seselj’s transfer to the Hague court would increase political pressure on Serbian Prime Minister Aleksandar Vucic and his Progressive Party before a snap parliamentary election on April 24.

It could boost Seselj’s popularity and help his Radical Party pass the threshold of 5 percent of votes required for entering parliament.

Vucic is a former protege of Seselj’s who broke with his party in 2008 to steer a more pro-Western course. Serbia is now a candidate to join the EU.

Seselj is charged in The Hague with inciting murder and ethnic persecution during wars in Bosnia and Croatia as Yugoslavia fell apart.