Tokyo, Massive flooding and landslides triggered by torrential rain in the Japanese prefecture of Kumamoto have claimed the lives of 18 people, while 14 others were reported missing, it was reported.

The 18 confirmed deaths were mostly in their 60s to 80s, with nine in the city of Hitoyoshi, eight in the town of Ashikita, and one in Tsunagi, reports Xinhua news agency.

Meanwhile, 16n people are feared dead in the village of Kuma, including 14 from a nursing home near the Kuma River, which overflowed and caused extensive flooding.

As floods and mudslides cut off roads and swept away buildings, more than 2,000 households in eight municipalities remained isolated on Sunday morning.

The Japan Meteorological Agency (JMA) asked residents to remain alert as torrential rain is likely to continue downpour in parts of western Japan through Tuesday.

The JMA raised heavy rain warnings in many parts of Kumamoto and neighbouring Kagoshima prefecture to the highest level on Saturday morning, the first time it has issued such high alerts for the two prefectures.

According to the agency, Amakusa in Kumamoto received record precipitation of 98 mm per hour.

About 203,200 residents in the two prefectures were asked to take shelter.

In 17 municipalities in Kumamoto, 109 shelters were opened to house at least 871 evacuees.

Due to extensive flooding along the Kuma River, the prefectural government asked for the dispatch of Ground Self-Defense Force personnel for disaster relief work.

Rescuers struggled to reach the hard-hit areas along the river which broke its banks at several locations early Saturday.

Prime Minister Shinzo Abe said at a disaster management meeting Sunday that he wants rescue workers to do their utmost to help people in distress and search for those missing "through the night".

Around 4,650 households in Kumamoto prefecture remained without power on Sunday afternoon, according to Kyushu Electric Power Co.

Shinkansen bullet train services in the prefectures have also been suspended, Kyushu Railway Co. said.