Frantic relatives scoured makeshift morgues in the Cambodian capital yesterday after almost 350 revellers perished in a huge stampede on an overcrowded bridge, turning a water festival into tragedy.

Survivors recounted scenes of panic and fear on the narrow bridge as people were trampled underfoot by the surging crowds on Monday, with some reportedly falling or jumping into the river below or grabbing on to electricity cables.

Prime Minister Hun Sen described the disaster as Cambodia’s darkest hour since the Khmer Rouge, whose 1975-1979 reign of terror left up to a quarter of the population dead.

“This is the biggest tragedy since the Pol Pot regime,” Hun Sen said in a live television broadcast, referring to the Khmer Rouge’s late leader.

He said Cambodia would hold a national day of mourning tomorrow.

It was not immediately clear what had triggered the disaster, but government spokesman Khieu Kanharith said a rumour had spread among revellers celebrating one of Cambodia’s biggest festivals that the bridge was unstable.

“So panic started. It was too crowded and they had nowhere to run,” he said. The toll from the stampede had risen to 349 people dead and more than 400 injured, with many of the deaths caused by suffocation and internal injuries, he said, adding that about two-thirds of the dead were women.

At the scene of the tragedy, sunglasses and flip-flops were scattered among lifeless bodies on Koh Pich bridge, still decked with lights from the huge annual water festival that drew millions into the streets on Monday night.

“We were crossing the bridge to Diamond Island when people started pushing from the other side. There was lots of screaming and panic,” 23-year-old Kruon Hay said at the scene. “People started running and were falling over each other. I fell too. I only survived because other people pulled me up. Many people jumped in the water,” he said.

Exuberant festival-goers had been crossing the bridge to reach an island hosting concerts, food stalls and ice sculptures before the crowd turned to a desperate crush of human bodies. Many witnesses reported seeing people jump or fall from the crossing into the river below.

“We are doing a search around the bridge in case there are bodies in the water,” the government spokesman said.