The rally against the Croatian government’s decision to make Serbian an official language in the war-ravaged town was followed by an alleged assault in a nearby village.
Some 20,000 members of Croatian war veterans’ associations rallied in the central square in Vukovar, a town devastated by heavy fighting when it was besieged by Serb forces in 1991.
"This is not Serbia," declared one of the banners carried by the protesters who demanded that the Croatian government must rethink the decision.
"Prime minister, don't provoke the defenders of Vukovar," warned protest organiser Tomislav Josic at the rally.
An hour after the protest, a Serbian Orthodox priest's son from the nearby village of Borovo said he was attacked in a café by three youths who were returning from the rally.
"One of them kicked me so I fainted and fell to the floor," 21-year-old Milan Lukic told journalists, claiming that police let the attackers go without intervening.
The government decided to introduce Serbian Cyrillic script alongside Croatian after the results of the 2011 census, which were published recently, showed that 34.87 per cent of Vukovar’s population are Serbs.
Croatia’s law on minority rights says that a minority has the right to the official use of its script and language in areas where it makes up more than the third of the population.
War veterans associations’ opposed the decision, saying that the introduction of Serbian should be postponed for at least 20 years, and recently filed a suit against the minority rights law at the constitutional court.
But Vukovar’s mayor Zeljko Sabo, also a war veteran who spent nine months in a Serbian prison after the town was seized in November 1991, said recently that the law must be applied.
Croatian Prime Minister Zoran Milanovic has also said that the government won't change its decision, “not only because of the rule of law, but because Croatia is a just country”.
President Ivo Josipovic said on Sunday that he "expects political parties to explain to citizens the importance of honouring the constitutional law".
"If we don't want to respect the law, we have to change it," Josipovic said.
Milorad Pupovac, president of the Serbian national council, the Serb local authority in Croatia, said he "doesn't see any reason for the postponement of bilingualism in Vukovar".
"The use of war rhetoric against Cyrillic [script] is intolerable and against the law, it's hate speech and an attack at the constitution and Croatian laws," Pupovac said.
The government’s decision caused anger because Vukovar became a symbol of Croatian resistance after it was besieged for three months and partly demolished by the Yugoslav Army and Serbian paramilitaries.
More than 1,600 people died and about 2,500 were wounded during the fighting, while the shelling of the town destroyed more than 8,000 buildings, including much of Vukovar's Austro-Hungarian architectural heritage.
After the town fell, all the remaining Croats were forced to leave and more than 200 wounded prisoners of war and civilians were taken from hospital to a nearby farm at Ovcara and executed.
Vukovar was returned to Croatia in 1998 but the majority of Serbs continued to live in the area.