Serbia's ultra-nationalist party leader Vojislav Seselj, who is being tried by a UN court for suspected war crimes, on Thursday underwent surgery to remove a tumour from his colon, his party said.
"He is recovering in a hospital" in the Netherlands, Serbian Radical Party deputy (SRS) leader Milorad Mircic told journalists without giving further details.
Seselj, who is 59, has been detained since February 2003. His party announced last year that he underwent heart surgery.
He is standing trial before the Hague-based International Criminal Tribunal for the former Yugoslavia, or ICTY for war crimes and crimes against humanity committed between 1991 and 1993 in Bosnia, Croatia and Serbia during the break-up of Yugoslavia.
His victims were civilians, mainly from the now defunct country's Croat and Muslim communities.
Since the start of his trial the ICTY has already sentenced him on three separate occasions for contempt of court.