A huge landslide swept away homes and left at least 20 people missing at a popular resort town in central Japan on Saturday after days of heavy rain, local officials said.

Television footage showed a torrent of mud obliterating some buildings and burying others in Atami, south west of Tokyo, with people running away as it crashed over a hillside road.

"I heard a horrible sound and saw a mudslide flowing downwards as rescue workers were urging people to evacuate. So I ran to higher ground," a leader of a temple near the disaster told public broadcaster NHK.

"When I returned, houses and cars that were in front of the temple were gone."

A Shizuoka prefecture disaster management official told AFP that "the safety of 19 people is unknown" after the landslide.

The local government has requested military assistance for a rescue mission, he said.

The landslide occurred at around 10.30am local time and "several houses were swept away", an Atami city official said.

#BREAKING: At least 20 missing following a series of major landslides in the Japanese city of Atami. pic.twitter.com/unfYpwnQyg

— UA News (@UrgentAlertNews) July 3, 2021

More than 2,800 homes in the region were without power, according to the Tokyo Electric Power Company (TEPCO).

A video posted on TikTok from the scene showed a huge slurry of mud and debris sliding slowly down a steep road and nearly engulfing a white car, which drove away before a faster and more devastating torrent arrived.

A road is covered in mud and debris following heavy rain in Atami city, Shizuoka prefecture

Credit: Satoru Watanabe via AP

Prime Minister Yoshihide Suga will meet ministers this afternoon to discuss the disaster and other rain-related damage, Japanese media reported.

Much of Japan is currently in its annual rainy season, which lasts several weeks and often causes floods and landslides, prompting local authorities to issue evacuation orders.

Experts say climate change is intensifying the phenomenon because a warmer atmosphere holds more water, resulting in more intense rainfall.

More than 200 people died as devastating floods inundated western Japan in 2018, and last year dozens more were killed as the coronavirus pandemic complicated relief efforts.

Atami saw rainfall of 313 millimetres in just 48 hours to Saturday – higher than the usual monthly average of 242.5 millimetres in July, according to NHK.

The city is around 90 kilometres (55 miles) from Tokyo and is famous as a hot spring resort.

Shinkansen bullet trains between Tokyo and Osaka were temporarily stopped due to the heavy rain, while other local trains in rain-affected areas were also halted, rail company websites said.