Police officers search for missing residents in a mud and rubble-covered residential area following a massive landslide in Hiroshima, western Japan, Thursday, Aug. 21, 2014 (Photo: AP)
The death toll from catastrophic landslides in western Japan could more than double, a police tally showed Friday, as fears of a fresh collapse halted the search for 51 people still missing.
At least 39 people were killed and dozens of homes were destroyed when mountainsides gave way on the outskirts of Hiroshima before dawn Wednesday, sending tonnes of mud, rocks and debris crashing into suburban communities.
More than 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".
The 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 remained unchanged Friday at 39, but the number of missing was raised, having climbed steadily over the last two days from initial single figures.
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.
Hiroshima Mayor Kazumi Matsui noted the clock was ticking and the 72-hour golden window, in which experts reckon survivors are most likely to be found, was closing.
"I want (rescuers) to save the lives of many missing people within these hours," the mayor told an emergency press conference in the city, according to Jiji Press news agency.
He dismissed charges that the city was too slow to issue evacuation advisories.
"We were cautious in making decisions as an easy issuance would hurt the confidence in advisories," he reportedly said.
Seven of the 39 confirmed dead have not been identified yet and could be among those counted as missing.
A body newly identified Friday was Kota Torigoe, 17, dashing hopes for members of his local high school baseball team who had been holding a vigil near his half-submerged house.
Firefighters and soldiers were still keeping heavy machinery away from collapsed houses, preferring to remove debris by hand in the hope of finding survivors.
But falling rain was complicating their task in an area where the hillsides are made of decomposed granite -- a coarse sand-like material that is used for driveways and paths, but which occurs naturally in this part of Japan.
Geologists say the rock is so weathered that it easily fractures into smaller chunks and becomes fragile when waterlogged.
Forecaster said heavy rain was expected in the afternoon, bringing with it the risk of further landslides.
Meteorologists said the downpour could continue until Saturday evening, with few breaks.
Heavy rain was also affecting parts of Japan further south.
In Shime town in Fukuoka prefecture, a 21-year-old police officer was swept away in a flooded gutter in the early hours of Thursday while trying to assess road conditions.
His body was found about two hours later in a river, a Fukuoka police spokesman said.
Chikushino city also in Fukuoka issued an evacuation advisory to all its 102,000 residents.