More than 100 people have been killed and dozens are missing after record torrential rains unleashed floods and landslides in western Japan.

Rescuers are searching for nearly 80 people who are still accounted for, most of them in the hardest-hit Hiroshima area.

Nearly 13,000 people have been left without electricity, power companies said on Monday, while hundreds of thousands had no water.

Heavy rain leads to flooding and landslides in Japan Show all 15 1 /15 Heavy rain leads to flooding and landslides in Japan Heavy rain leads to flooding and landslides in Japan People await resuce in Kurashiki, Okayama prefecture AP Heavy rain leads to flooding and landslides in Japan A car stands on its nose in Okayama prefecture as flooding hits Japan Getty Heavy rain leads to flooding and landslides in Japan A rescue helicopter is on the scene of a landslide in Iwakuni, Yamaguchi prefecture AP Heavy rain leads to flooding and landslides in Japan An emergency crew attends to a train that has been derailed by a tree on the tracks. Heavy rain has caused landslides in Saga prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Kurashiki, Okayama prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan A car is trapped in mud flows in Saka, Hiroshima prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Kurashiki, Okayama prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Rescue teams transport people from the Mabi Memorial Hospital in Kurashiki, Okayama prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Kurashiki, Okayama prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Soldiers search for victims in Kurashiki, Okayama prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan A road is damaged in Kurashiki, Okayama prefecture AP Heavy rain leads to flooding and landslides in Japan Rescue teams attend to inpatients, staff and residents at the Mabi Memorial Hospital in Kurashiki, Okayama prefecture EPA Heavy rain leads to flooding and landslides in Japan Kurashiki, Okayama prefecture EPA Heavy rain leads to flooding and landslides in Japan Police clear debris in Kumano, Hiroshima prefecture AFP/Getty Heavy rain leads to flooding and landslides in Japan Residents take shelter in an evacuation centre in Kurashiki, Okayama prefecture AFP/Getty

It is the worst flood disaster since 1983, when 117 people were killed in heavy rains.

The death toll reached at least 110 after floodwaters forced several million from their homes, NHK public television said on Monday, with another 79 people missing.

Many areas have been left flooded after days of record rainfall (AFP/Getty) (JIJI PRESS/AFP/Getty Images)

Though the continuous rain had ended, officials warned of sudden showers and thunderstorms, as well as the risk of further landslides on steep mountainsides saturated over the weekend.

Some homes had been smashed, while others were left tilting precariously.

Rivers had overflowed, flooding towns and turning them into lakes, leaving dozens of people stranded on rooftops. Military paddle boats and helicopters have been used to bring people to dry land.

Some homes have been smashed while others were left tilting precariously (AFP/Getty) (MARTIN BUREAU/AFP/Getty Images)

The Japan Meteorological Agency said three hours of rainfall in one area in Kochi prefecture reached an accumulated 26.3 centimetres (10.4 inches), the highest since such records started in 1976.

The government set up an emergency taskforce over the weekend and has sent troops, firefighters, police and other disaster relief. People have also pleaded for help on social media.

A car stands on its front after heavy flooding (Getty) (Carl Court/Getty Images)

Although evacuation orders were scaled back from the weekend, nearly two million people still face orders or advice to keep away from homes, fire and disaster officials said.