At least 31 people were killed after a week of torrential rains triggered flash floods and landslides across Indonesia's North Sumatra province, authorities said on Friday.

The disaster has affected four districts, from Medan to rural areas like Sibolangit and Sayur Matinggi, where the landslides have severed access for communities with roads buried under debris, Indonesia's disaster agency said.

Rescuers are working under treacherous circumstances to clear access routes and search for missing persons while temporary shelters are becoming overburdened to accommodate the displaced.

The head of North Sumatra's disaster management agency, Tuahta Ramajaya Saragih, said that the agency has submitted a request to the provincial governor to declare a disaster emergency status.

"High-intensity rainfall continues to batter the region, and we expect the risk of further disasters to remain elevated until at least early December," he said.

The proposed status would expedite aid distribution and mobilize national resources to help thousands of displaced residents.

Search for survivors

On Friday, police and rescue officials continued a search for survivors buried in three cars and a tourist bus at the bottom of a cliff after a landslide on the road from Medan city to Berastagi on Wednesday.

The hilly interprovincial road is the main route from the capital, Medan, to other districts in the region.

The number of deaths from the landslide increased from seven to nine, officials said on Friday as rescuers recovered more bodies from the bus which was buried underneath trees, mud and rocks.

"We still don't know how many people who were still trapped," a spokesperson of North Sumatra police told Reuters on Friday.

More than 10 others were injured in the incident.

Indonesia — a tropical archipelago of 17,000 islands where millions of people reside in mountainous areas or near fertile floodplains — frequently sees flooding and landslides from seasonal rains from October to March, 

Indonesia's weather agency has warned of extreme weather toward the end of the year as the La Nina phenomenon accelerates rainfalls across the country.

dvv/zc (Reuters, dpa, AP)