Heavy monsoon season rains paired with a tropical storm system inundated areas across the three countries, stranding residents on rooftops and cutting off entire communities.

Authorities in Indonesia were struggling to reach the worst-affected areas on Sumatra island, while authorities at a southern Thailand hospital brought in refrigerated trucks to store bodies after the morgue exceeded capacity.

In Indonesia's West Sumatra province, 53-year-old Misniati described a terrifying battle against rising floodwaters to reach her husband at home.

She said that, returning from early morning prayers at a mosque, "I noticed the street was flooded."

"I tried to run back to my house to tell my husband, and the water was already reaching my waist," she told AFP, adding that it was up to her chest by the time she reached home.

"We didn't sleep at all last night, we just monitored the water," said Misniati, who only uses one name.

Officials on Sumatra said flooding and landslides this week had killed at least 174 people, with nearly 80 more missing.

National Disaster Mitigation Agency (BNPB) chief Suharyanto said the toll could grow as rescuers reach isolated areas.

"There are locations that still cannot be reached... where it is indicated that there may be human victims in those areas that are unreachable," Suharyanto said.

North Sumatra police spokesman Ferry Walintukan said authorities were focused on "evacuation and providing assistance", although access to some areas and communication was still cut.

"Hopefully, the weather will clear up so we can move the helicopter to the (worst-hit) locations," he said.

In Aceh province in Sumatra's north, receding water left behind cars buried in mud almost up to their windows. An AFP journalist saw a truck carrying timber abandoned in the mud, with no sign of the driver.

More rain is forecast for much of Sumatra island, although the intensity was expected to ease, officials said.

- 'Nothing I could do' -

Among the hardest-hit areas in the region is southern Thailand, where residents of Hat Yai were left clinging to rooftops awaiting rescue by boat.

At least 145 people have been killed across Thailand's south, government spokesman Siripong Angkasakulkiat said on Friday, as receding floodwaters allowed a clearer picture of the disaster.

Most occurred in Songkhla province, where authorities at the Songklanagarind Hospital said they had no more room for bodies and were relying on refrigerated trucks.

"The morgue has exceeded its capacity, so we need more," Charn, a morgue official who only gave his first name, told AFP.

There has been growing public criticism of the flooding response and two local officials have been suspended over their alleged failures.

Hat Yai residents described floodwaters rising rapidly.

"The water rose to the ceiling of the second floor," said Kamban Wongpanya, 67, who had to be rescued by boat.

Shop owner Rachane Remsringam said his general goods store Madam Yong was looted and vandalised by flood victims.

"Many kitchen products and food items were stolen, including sugar and milk," he told AFP, saying that the damage amounted to several hundreds of thousands of dollars.

AFP footage showed the shop littered with rubbish and empty shelves.

Two people were killed in Malaysia by flooding caused by heavy rain that left stretches of northern Perlis state under water.

- 'Extreme weather' -

The annual monsoon season, typically between June and September, often brings heavy rains, triggering landslides and flash floods.

A tropical storm has exacerbated conditions, and the tolls in Indonesia and Thailand rank among the highest in flooding events in those countries in recent years.

Climate change has affected storm patterns, including the duration and intensity of the season, leading to heavier rainfall, flash flooding and stronger wind gusts.

A warmer climate holds more moisture, producing more intense rain events, while warmer oceans can turbocharge the strength of storm systems.

"Climate scientists have already warned that extreme weather events... will continue to worsen as temperatures increase," said Renard Siew, climate change adviser to the Centre for Governance and Political Studies in Malaysia.

"That is exactly what we have been seeing."

burs-sah/pbt