The event went ahead after the national Covid-19 response team ruled that a ban on gatherings of more than 50 people does not apply to rallies marking public holidays such as Vukovar Remembrance Day.

An association of hospital doctors slammed the decision for "hypocrisy and cowardice", saying measures to fight the virus should be "valid for all of us in all situations".

Despite an official recommendation that only 500 people attend Wednesday's commemoration, around 10,000 people took part in a traditional silent march through the eastern town, according to local media.

The mourners, many not wearing masks, first gathered in front of a hospital that symbolises Vukovar's wartime resistance and then marched to the cemetery to lay wreaths and light candles.

Croatia, with a population of some 4.2 million, has registered more than 90,000 infections and 1,151 deaths from Covid-19.

A record 3,251 cases were registered on Wednesday.

The Vukovar event usually draws tens of thousands remembering "Croatia's Stalingrad" when the city fell after a three-month siege by the Serbia-controlled Yugoslav army (JNA) and Serb rebels.

The city was practically razed to the ground and more than 1,600 people were killed.

Soldiers bused about 260 people to a secluded pig farm where they were beaten, killed and buried in mass graves.

Some 22,000 non-Serbs were expelled from the area.

Deputy Prime Minister Boris Milosevic, an ethnic Serb, joined the mourners Wednesday.

Prime Minister Andrej Plenkovic hailed his presence as an important "message turned towards future".

A quarter century on, relations between Croatia and its ethnic Serbs and Serbia proper remain tense, and Vukovar is strictly divided between ethnic Croats and Serbs.

A UN war crimes court sentenced two top Serb officers, Mile Mrksic and Veselin Sljivancanin, to jail terms of 20 and 10 years for the Vukovar massacre.

Croatia's proclamation of independence from Yugoslavia sparked the 1991-95 war with Belgrade-backed rebel Serbs who opposed the move.

The conflict claimed 20,000 lives.