"As of Sunday, 20 people were killed... And 88 people were still missing," the National Disaster Management Agency spokesman Sutopo Purwo Nugroho said.
Fifteen people were injured, including 11 seriously, and 577 people were evacuated to temporary shelters, he added.
Around 1,250 rescuers, including police, soldiers and volunteers, were digging with shovels through mud and rubble to look for victims after torrential downpours triggered a landslide and hit Jemblung village in central Java late Friday.
President Joko Widodo was travelling from the capital Jakarta to Central Java's provincial district of Banjarnegara today to meet with survivors.
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"We are trying our best to look and evacuate those still buried. It's a big challenge because we are still using manual tools and the affected area is very muddy," Banjarnegara district military commander Edi Rahmatullah told reporters.
Landslides triggered by heavy rains and floods are common in tropical Indonesia during the rainy season.
The national disaster agency estimates around half the country's population of 250 million lives in areas prone to landslides.