Japan is struggling to restore utilities and bring relief to the victims of its worst floods in 36 years, as the death toll rises to 157 with dozens still missing.

Key points: More than 60 people are still unaccounted for, mostly in Hiroshima

More than 60 people are still unaccounted for, mostly in Hiroshima High temperatures in the 30s are causing extra health issues and hindering rescue efforts

High temperatures in the 30s are causing extra health issues and hindering rescue efforts The Government mobilised 75,000 troops and nearly 80 helicopters to assist rescue efforts

Torrential rains unleashed floods and landslides in the west of the country last week, prompting Prime Minister Shinzo Abe to cancel an overseas trip to cope with the disaster, which at one point forced several million from their homes.

Mr Abe will visit the worst-hit areas to survey the damage and visit local communities as rescuers continue to search for survivors.

The landslides and flooding across much of western Japan have killed at least 157 people, Chief Cabinet Secretary Yoshihide Suga said.

Rescuers continue to search for survivors in Kumano town, Hiroshima prefecture, as dozens of people remain missing. ( AP: Kota Endo/Kyodo News )

Dozens of people were still unaccounted for as of this morning, many in the hardest-hit Hiroshima and Okayama areas.

Rescuers were combing through mud-covered hillsides and along riverbanks, with many citizens facing health risks from high temperatures and a lack of water.

"No water, food, nothing gets here," Ichiro Tanabe, a 73-year-old Kure resident, told the Mainichi newspaper.

"We are going to be all dried up if we continue to be isolated."

Power supply has now resumed to all but 3,500 customers, but more than 200,000 remain without water under scorching sun, with temperatures set to hit 33 degrees Celsius in some of the hardest-hit areas, such as the city of Kurashiki.

Rescuers conduct a search for missing people in Kumano, Hiroshima prefecture, western Japan. ( AP: Sadayuki Goto )

The Japan Meteorological Agency said as much as 10 centimetres of rain per hour fell on large parts of south-western Japan.

"There have been requests for setting up air-conditioners due to rising temperatures above 30 degrees today, and at the same time we need to restore lifelines," Finance Minister Taro Aso said after a cabinet meeting on Tuesday.

Some residents shrugged off warnings

Roads coated in dried mud in the Mabi district of Kurashiki threw up clouds of dust when rescue vehicles or cars drove by.

Survivors recounted narrow escapes.

"It was close. If we had been five minutes later, we would not have made it," said Yusuke Suwa, who fled by car with his wife early on Saturday when an evacuation order came after midnight.

"It was dark and we could not see clearly what was happening, although we knew water was running outside. We did not realise it was becoming such a big deal."

Sorry, this video has expired A resident is rescued from a submerged house in Kurashiki. (Photo: Reuters/Kyodo)

A quarter of flood-prone Mabi, sandwiched between two rivers, was inundated after a levee crumbled under the force of last week's torrents.

But some residents of Mabi had shrugged off the warnings, however, given the area's history of floods.

"We had evacuation orders before and nothing happened, so I just thought this was going to be the same," said Kenji Ishii, 57, who ignored an order and stayed in his home with his wife and son.

A military boat plucked them from the second floor of the house, where they had fled to escape the rising waters.

"When rescue boats started coming around, they could find people looking out from the window, but those who stayed inside the house were not visible to them," Mr Ishii added.

A new evacuation order went out on Tuesday in a part of Hiroshima prefecture, after a river blocked by debris overflowed its banks, affecting 23,000 people.

Government pumps money into rescue and recovery

Sorry, this video has expired Heavy rains have caused flooding and landslides across western Japan. (Photo: AP/Kyodo News)

Mr Abe cancelled a planned July 11-18 trip to Europe and the Middle East to oversee the emergency response.

The Government mobilised 75,000 troops and emergency workers and nearly 80 helicopters for the search and rescue effort, Mr Suga said.

The Government has set aside 70 billion yen ($845 million) in infrastructure funds to respond to disasters, with 350 billion yen ($4.22 billion) in reserve, Mr Aso said, adding that an extra budget would be considered if needed.

The roof of a house is left in the middle of a road in Kurashiki, Okayama prefecture. ( AP: Yohei Nishimura/Kyodo News )

Mr Suga added that the Government has set up a taskforce and was spending 2 billion yen ($24 million) to hasten deliveries of supplies and other support for evacuation centres and residents in the region.

"When necessary amounts firm up … we would consider an extra budget later on if these funds prove insufficient," Mr Aso said.

Japan monitors weather conditions and issues warnings early, but its dense population means every bit of usable land, including potential flood plains, is built on in the mostly mountainous country, leaving it prone to disasters.

People wait to be rescued on the top of a house after heavy rainfall in Kurashiki. ( AP: Kyodo )

AP/Reuters