MANDAILING NATAL (Sumatra) • At least 22 people have died and many are missing after heavy rain unleashed flash floods and landslides in western Indonesia, an official said yesterday.

Heavy downpours since last Wednesday triggered flooding and landslides that hit several districts on Sumatra island.

At least 17 people were confirmed dead in the past three days in North Sumatra province, while five others were killed in West Sumatra, the authorities said.

Eleven students at an Islamic boarding school in Muara Saladi village in Mandailing Natal district, North Sumatra, died last Friday when mud and debris from a landslide smashed into their school, said national disaster agency spokesman Sutopo Purwo Nugroho.

Scores of people were believed to be buried under the mud after the flash floods, and the death toll might rise as assessment of the aftermath was still under way, he was quoted by Xinhua as saying.

Dozens of houses have also been destroyed.

"The disaster and search and rescue agency have gone to the districts but have been hampered by the landslides in several areas," head of the North Sumatra disaster agency Riadil Lubis told Agence France-Presse.

Landslides and flooding are common in Indonesia, a vast tropical archipelago prone to natural disasters and torrential downpours.

In February, 12 people died when an avalanche of mud and rock cascaded down a steep slope in central Java, Indonesia's main island.

In June 2016, nearly 50 people died when heavy downpours sent torrents of water, mud and rock into villages in Central Java.

AGENCE FRANCE-PRESSE, XINHUA