The vandals sprayed a Serb symbol on the memorial to 24 Croatians who were killed during wartime and buried in a mass grave near the city of Vukovar.
The memorial at a farm in the eastern Croatian village of Lovas was spraypainted with four Cyrillic letters which represent a well-known Serbian slogan, ‘Only Unity Can Save the Serbs’.
The Croatian war veterans ministry condemned the incident, which took place on Monday according to local media.
“The desecration of a memorial is the worst insult to the victims of war crimes and their families, but to all Croatia’s citizens as well,” the ministry said in a statement, expressing hope that perpetrators will soon be found.
Twenty-four victims of the 1990s conflict were exhumed from the mass grave at the farm in 2001 and a monument of a white dove carved into black stone was placed there as a memorial.
The monument was vandalised amid continuing public controversy about government plans to bring Cyrillic script and the Serbian language into official use in Vukovar and other areas of the country.
Around 20,000 protesters rallied against the move this month in Vukovar, a town devastated by heavy fighting when it was besieged by Serb forces in 1991.
Croatian minority rights law 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, such as Vukovar, where around 35 per cent of residents are Serbs.