TOKYO: More than a thousand Japanese rescuers combed through crumbled houses and buried roads on Monday two days after landslides tore through a seaside city, fighting time and poor weather to search for some 80 people believed missing.

At least three people have been killed in Atami after torrential rain at the weekend - more than a usual July's worth in 24 hours some areas - touched off a succession of landslides, sending torrents of mud and rock ripping through streets.

The landslides are a reminder of the natural disasters - including earthquakes, volcanic eruptions and tsunami - that haunt Japan, where the capital Tokyo is to host the summer Olympics beginning this month.

"My mother is still missing," one man told NHK public television. "I never imagined something like this could happen here."

One 75-year-old evacuee said the house across from his had been swept away and the couple that lived there was unaccounted for.

"This is hell," he said.

By Monday, the number of rescuers at the site had risen to 1,500, officials said, and could increase.

"We want to rescue as many victims ... buried in the rubble as soon as possible," Prime Minister Yoshihide Suga told reporters, adding that police, firefighters and members of the military were doing all they could to aid the search.

There are 113 people believed missing in Atami, a city of almost 36,000 people situated 90 km (60 miles) southwest of Tokyo, spokesperson Hiroki Onuma told Reuters, confirming the third death. That fatality was a woman, Japanese media said

By noon, though, that number of missing had dropped to around 80, Kyodo said.

"We're in touch with various groups and pushing forward with the searches," Onuma said.

Over the weekend some 20 people were said to be unaccounted for, but the number rose sharply on Monday as officials began working from residential registers rather than phone calls from people unable to reach family and friends, he said.

Around 130 buildings were affected on Saturday morning when landslides ripped through Atami, a hot springs resort set on a steep slope that leads down to a bay.

The water, mud and debris are thought to have flowed along a river for about 2 km (1.2 miles) to the sea, local media said.

Chief Cabinet Secretary Katsunobu Kato called on residents to remain vigilant, noting that the saturated earth has been weakened and even light rain could prove dangerous.

Though Onuma said rain had stopped in Atami for now, more is forecast, raising the possibility of further landslides.

"The situation is unpredictable," he said.

Stocks in some engineering firms rose on Monday.

Raito Kogyo Co Ltd, an expert in slope and foundation improvement, rose 1.5%, while CE Management Integrated Laboratory Co Ltd, which offers geological survey and disaster prevention systems, gained 3.7%.