The death toll from floods and landslides on the Indonesian island of Sumatra island has risen to 174, up from the previous 94, the country's disaster mitigation agency said on Friday, adding that dozens remain missing.

A total of 303 people died and 279 remain missing after flash floods and landslides struck three provinces in Indonesia's Sumatra region, the country's National Disaster Management Agency (BNPB) said on Saturday, Xinhua reports.

BNPB Chief Suharyanto told a press conference that North Sumatra suffered the highest number of casualties, with 166 deaths and 143 people still unaccounted for. In West Sumatra, 90 people were confirmed dead and 85 missing, while in Aceh, 47 fatalities were recorded and 51 people remained missing.

The number of people killed by floods and landslides on Indonesia's Sumatra island rose to 708 on Dec 2, the disaster agency said, as authorities rushed to repair infrastructure and deliver aid to cut-off areas.

The agency in a press conference late on Dec 2 said 708 people had been killed since last week, a figure lower than the 753 reported on its website earlier in the day. It did not give a reason for the discrepancy.

Close to 900 people have been killed in floods and landslides that have wreaked havoc in Indonesia, Malaysia and Thailand, which follow months of adverse and deadly weather in South-east Asia, including successive typhoons that struck the Philippines and Vietnam and added to frequent and prolonged flooding elsewhere.

Residents in Indonesia's Aceh Tamiang district were forced to scramble over fallen trees and wrecked vehicles on Saturday (December 6) as they made a gruelling hour-long walk to reach emergency supplies, with the death toll from this month's devastating floods and landslides on Sumatra now exceeding 900.

Cyclone-driven downpours have triggered floods and landslides across three provinces on Sumatra, including Aceh, killing 908 people and leaving 410 still unaccounted for, according to government figures released on Saturday.

The same storm systems have also claimed about 200 lives in southern Thailand and Malaysia.

Southern Thailand is confronting its most severe flooding in over three centuries as relentless monsoon rains have killed at least eight people and affected nearly 2 million residents across 10 provinces.

The southern trading hub Hat Yai district in Songkhla province recorded its heaviest single-day rainfall in more than 300 years, prompting authorities to declare all 16 districts in Songkhla a disaster zone.

Thailand has experienced heavy rain, leading to a flood that has resulted in 41 deaths and impacted more than 2.68 million people nationwide.

Songkhla Province is the most severely affected area by this disaster.

The Thai government declared a state of emergency in the province on Tuesday.

The death toll from devastating floods across southern Thailand has risen to 145, with more than 100 people killed in the hard-hit Songkhla province alone, according to the government.

Devastating flooding has overwhelmed southern Thailand this week, particularly in the Hat Yai district, near the border with Malaysia.

The "total deaths across the southern provinces is 145", with Songkhla accounting for 110, government spokesman Siripong Angkasakulkiat told a news conference on Friday, updating earlier figures.

He said search and rescue efforts have become more successful as floodwaters started to recede further.

News reports showed rescuers gained more access to residential areas that had previously been submerged under high water, and recovered more bodies, particularly in Hat Yai, the largest city in the south.