UN prosecutors Wednesday sought to overturn the surprise acquittal on war crimes charges of an ultranationalist Serbian politician, arguing last year's ruling had been deeply flawed.
"Your Honours, justice has not been done in the case against Vojislav Seselj," said prosecutor Mathias Marcussen, adding his office had "identified numerous errors" in the 2016 ruling which found Seselj not guilty on nine counts of war crimes and crimes against humanity.
Seselj himself snubbed the appeal hearing, which comes after several recent blows for the International Criminal Tribunal for the former Yugoslavia (ICTY) and its work to prosecute those behind the atrocities of the 1990s Balkans wars.
The setbacks included the dramatic suicide of former Bosnian Croat military commander Slobodan Praljak, who swallowed cyanide in the courtroom in late November just after judges upheld his 20-year jail term for war crimes.
A week earlier, Bosnian Serb military commander Ratko Mladic had to be dragged from the courtroom during an angry outburst as he was jailed for life for genocide, among other charges.
The "stunning" judgement against Seselj was not up to the tribunal's standards and "must be quashed. Letting it stand will undermine the credibility both of the ICTY" and its successor, the Mechanism for International Criminal Tribunals (MICT), Marcussen told the five appeals judges on Wednesday.
Set up in 1993, the ICTY has successfully prosecuted dozens of those responsible for the worst atrocities in Europe since World War II. But hopes of bringing reconciliation to the bitterly divided region remain distant.
In a sign of lasting tensions, about 2,000 people packed a public memorial in Zagreb on Monday to honour Praljak as a hero.
Addressing the event, Miroslav Tudjman, a lawmaker of Croatia's conservative HDZ party and son of the late Croatian nationalist Franjo Tudjman, slammed the UN judges as "incompetent and irresponsible" and said the court is "a parody, a theatre of the absurd".
Seselj, 63, now a member of the Serbian parliament with his Serbian Radical Party, has done little to hide his contempt for the tribunal, and refused to travel back from Belgrade for the hearing.
"Since I was acquitted in the first instance, I do not see what is left for this mechanism, what it can do with my verdict," Seselj told AFP.
But prosecutors insist Seselj was behind the murders of many Croats, Muslims and other non-Serb civilians in an unrelenting quest to create a "Greater Serbia" in the 1990s.
In their majority ruling in March 2016, trial judges said the prosecution failed to prove "there was a widespread systematic attack against the non-Serb civilian population in large areas of Croatia and Bosnia-Hercegovina."
But on Wednesday, the prosecution hit back that this was a "stunning finding" which was "at odds with dozens of other judgements rendered at the ICTY."
"The majority failed to consider the vast body of evidence" of crimes committed in Bosnia-Hercegovina and Croatia, Marcussen said.
He also disputed findings that the prosecution failed to prove any "causal link" between Seselj's fiery speeches and the wave of atrocities.
"It is clear from the totality of the evidence that there was an increase in the acts of violence" following Seselj's speeches, he told Wednesday's hearing, which lasted barely just over an hour.
Experts said last year's judgement had overturned international law and rewritten the history of the Balkan conflicts, triggered as Yugoslavia broke apart in 1991 following the fall of communism.
The court's chief prosecutor Serge Brammertz has insisted that "in large measure, the ICTY has achieved what it set out to do" by investigating crimes and prosecuting top officials.
But he agreed at a Washington think-tank talk on Tuesday that reconciliation remained elusive, saying the tribunal's legacy would not be measured by its own work but by "whether the countries of the former Yugoslavia build the rule of law".
A ruling in the Seselj appeal is due in early 2018.