The death toll from catastrophic landslides in western Japan could more than double, a police tally showed Friday, as fears of a fresh collapse temporarily halted the search for 47 people still missing.

The death toll from catastrophic landslides in western Japan could more than double, a police tally showed Friday, as fears of a fresh collapse temporarily halted the search for 47 people still missing.

At least 40 people were killed and dozens of homes were destroyed when mountainsides gave way on the outskirts of Hiroshima before dawn Wednesday, sending tons of mud, rocks and debris crashing into suburban communities.

Over 4,000 people have now been ordered to evacuate their homes as more rain pelted already soaked hillsides, adding to the misery caused by this week's record downpours.

Firefighters, police and soldiers were forced to suspend search efforts on Friday afternoon when the shape of the mountains appeared to change, heralding a possible new landslip.

"Operations in (two districts) were halted as mountains there were becoming misshapen," a Hiroshima police spokesman said. Rescuers have been "evacuated as there is a risk of a fresh landslide".

Operations resumed later in the day.

"We will continue our search all night long tonight as we are really fighting against time," said Hideyuki Okuda, an official of the city's disaster management.

The suspension order came two days after a rescuer was killed when he was buried by a secondary landfall as he tried to carry a three-year-old boy to safety, following one of the worst mudslides in recent years.

The confirmed death toll ticked up to 40 on Friday, but the number of missing swelled from the initial single figures given two days earlier to 47, having been beyond 50 earlier in the day.

Officials said improved coordination between emergency services and local authorities meant they were now aware of more people who had not been heard of since the disaster.

"We initially counted only the people who were certain to be missing, such as those witnessed being carried away in gushing water," said a spokesman at Hiroshima prefecture police.

"As we continued to investigate and assess the situation, the number rose," he said.