Vojislav Seselj said Thursday he will "never go back there voluntarily."
The U.N. tribunal in The Hague, Netherlands, last year acquitted Seselj of war crimes during the 1990s' Balkan wars, but prosecutors have appealed.
The hearing is due to be held at a court handling appeals from the tribunal, which closes its doors at the end of the month.
Prosecutors originally charged Seselj with crimes including persecution, murder and torture for his support of Serb paramilitaries during the wars in Croatia and Bosnia. Seselj spent years in the tribunal custody after surrendering in 2003.
Seselj, who leads the Serbian Radical Party, is a member of parliament.
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