Rescuers, using rubber rafts to reach victims, predicted the death toll would climb.

Health Ministry Crisis Center chief Rustam Pakaya said the decades-old dam, which burst at around 2 a m (local time) following hours of torrential rain, completely destroyed some houses and inundated at least 400 others.

In some places water levels reached rooftops and Metro TV footage showed several bodies floating amid chairs, clothing and other debris. Telephone lines were toppled and cars swept away, some hundreds of metres.

"A flash flood came suddenly and was horrifying," said Seto Mulyadi, who said the water smashed all the windows and doors of his house, while he, his wife and four children were sleeping upstairs. "My house is a dreadful mess ... Thank God my family is safe".

Some residents living near the dam said they heard sirens before the disaster.