Thousands of Croats gathered Wednesday in Vukovar to mark the 18th anniversary of the town's capture by Serbs, one of the bloodiest events of the war following the break-up of Yugoslavia.

Some 20,000 mourners marched through the town to a cemetery and memorial, where they laid wreaths and lit candles in honor of the 1,600 defenders and civilians killed in the fighting, national television reported.

A commemoration was also held in front of the Vukovar's hospital, from where Serb forces pulled some 200 people and later executed them at a nearby pig farm.

- It was a deliberate and planned crime like Srebrenica - said President Stipe Mesic, who attended the commemoration.

Vukovar was razed after falling into Serb hands following a three-month-long siege, and some 22,000 non-Serb survivors were expelled from the area.

But the Vukovar battle was also crucial for Croatia's survival, stalling Belgrade-backed forces long enough for Zagreb to arm itself and prepare troops.

After the war, Vukovar and the whole region were placed under United Nations administration and later reintegrated into Croatia in 1998.

In 2007, the UN war crimes tribunal in The Hague convicted two Serb officers, Mile Mrksic and Veselin Sljivancanin, for the Vukovar massacre and sentenced them to 20 and five years in prison, respectively.

Earlier this year the court's appeals chamber increased Sljivancanin's prison sentence to 17 years.

Serbia's war crimes court in May also jailed 13 Serbs for up to 20 years over the Vukovar massacre.