Government officials said they feared the death toll in East Java could rise further, as a number of people were still reported missing. Thousands of people near Jember, 800km (500 miles) east of Jakarta, are thought to have been made homeless. Continued flooding has been hampering rescue efforts, emergency crew say.
Thirty-six hours after the floods hit, police, soldiers, villagers and volunteers are still pulling bodies from the sludge and wreckage. The deluge hit when a river burst its banks after days of heavy rain, triggering landslides that buried hundreds of houses.
"The death toll has reached 51," disaster management official Muhammad Suryadi told Reuters news agency.
"More than 300 can't get out [of their villages]," he added. "If the weather is good, rescuers will build emergency bridges to reach those areas today."
According to Tim Johnston in Jakarta, thousands of people have taken refuge on higher ground and, fearful of further flooding, are too frightened to go back down to their houses.
The government and aid groups are scrambling to get food, water and medical assistance to the displaced. Environmentalists say that much of the forest cover in the area - which would normally absorb some of the rain and prevent the hillsides from slipping - has been cut down in recent years, contributing to the disaster.
Indonesia is no stranger to flash flooding and landslides, especially during the rainy season between November and March, but the situation has been made worse by environmental degradation.
In the last year the government has made significant progress in fighting the illegal timber trade, our correspondent says. But much work remains to be done.
Source: BBCLast Mod: 20 Eylül 2018, 18:16