Villagers carry the body of a victim after flash floods in Indonesia. Picture used for illustrative purposes only.

The death toll from flash flooding and landslides on the Indonesian island of Sumatra has risen to 26, an official said Monday, with at least 11 people still missing.

Torrential rains on Thursday triggered the disaster in West Sumatra province, where rivers overflowed and landslides swallowed homes.

"Eleven people are still missing while 26 others have been found dead," Abdul Muhari, spokesman for the National Disaster Mitigation Agency, said in a statement Monday.

In the district of Pesisir Selatan, 23 people were found dead and six were still missing, according to Fajar Sukma, an official from West Sumatra's disaster mitigation agency.

Three other victims were found dead in Padang Pariaman district, which also suffered heavy damage.

Rescue efforts have been hampered by extreme weather and spotty electricity, Sukma said.

"It is still raining today and rescuers are conducting the rescue operation in the middle of the rain.

"There's a possibility that the number of casualties will continue to rise as we update the report," he said.

Sukma said that as of Sunday, rescuers had managed to open access to the most affected areas and distribute aid to evacuees, including tents, medicines, and instant food.

The disaster has damaged hundreds of houses, bridges, mosques, and other public facilities.

Indonesia is prone to landslides during the rainy season and the problem has been aggravated in some places by deforestation, with prolonged torrential rain causing flooding in some areas of the archipelago nation.

A landslide and floods swept away dozens of houses and destroyed a hotel near Lake Toba on Sumatra in December, killing at least two people.

Associated Press