South-East Asia flood deaths rise as Cyclone Ditwah hits Sri Lanka, heads towards southern India

The death toll from floods across large swathes of South-East Asia has risen to at least 420, with authorities working to rescue stranded citizens, restore power and communications, and coordinate recovery efforts as the waters began to recede.

Large parts of Indonesia, Malaysia and Thailand have been stricken by cyclone-fuelled torrential rain for a week, with a rare tropical storm forming in the Malacca Strait.

Additionally, another 123 people were killed by Cyclone Ditwah in the South Asian island nation of Sri Lanka, authorities said, and 130 remain missing amid widespread floods.

About 44,000 people have been displaced and are in temporary shelters, Sri Lanka's disaster management centre said.

Most deaths were caused by landslides triggered by more than 300mm of rainfall in the eastern and central regions, according to officials. 

Torrential rain and strong winds have been forecast to cause more flooding.

Schools have been shut, and train services have been suspended.

More than 20,000 police and military personnel have been coordinating evacuations in multiple towns, including the outskirts of Sri Lanka's largest city Colombo, after authorities warned of rising flood waters.

The country's air force said 13 people trapped on a bridge in Polonnaruwa, 220 km north-east of Colombo, had been airlifted.

Numerous families trapped on rooftops and one man stranded on top of a coconut tree were also airlifted to safety.

Heavy rains have also disrupted operations at Colombo's Bandaranaike International Airport, forcing the diversion of 15 flights.

India has delivered 6.5 tonnes of food aid to assist in relief efforts, the Indian High Commission in Colombo said, as Cyclone Ditwah moved northward across Sri Lanka towards southern India.

Indonesians stranded by metre-deep floodwaters

On Indonesia's badly hit Sumatra island, 303 people were confirmed dead on Friday, officials said.

The National Disaster Management Agency, or BNPB, said rescuers in West Sumatra's Agam district had recovered more bodies and that more than 500 people were injured. They feared the death toll would rise further.

While the rain had stopped, 79 people were still missing and about 3,000 displaced families fled to government shelters.

Monsoon rains over the past week caused rivers to burst their banks in North Sumatra province.

The deluge tore through mountainside villages, swept away people and submerged thousands of houses and buildings, the BNPB said.

"Mudslides that covered much of the area, power blackouts and lack of telecommunications were hampering the search efforts," Suharyanto said.

Residents in Sumatra's Padang Pariaman region, where a total of 22 people died, had to cope with water levels at least 1 metre high, and had still not been reached by search-and-rescue personnel on Friday.

Communications remained down in some parts of the island.

Authorities have been trying to restore power and clear roads blocked by landslide debris.

More aid and rescue personnel will be airlifted into areas where they are needed, authorities said.

Indonesian President Prabowo Subianto said three aircraft carrying rescue personnel, food, medicines, blankets, field tents and generators were deployed on Friday morning as part of ongoing relief operations.

"We continue to send aid and support the needs of those affected," he said.

"Many roads are cut off, and the weather remains unfavourable. Even our helicopters and planes sometimes struggle to land," he added.

Prabowo said the disaster highlighted growing global challenges such as climate change, global warming and environmental degradation.

The extreme weather was driven by Tropical Cyclone Senyar, which formed in the Strait of Malacca, said Achadi Subarkah Raharjo at Indonesia's Meteorology, Climatology and Geophysical Agency.

He warned that unstable atmospheric conditions meant extreme weather could persist as long as the cyclone system remained active.

Senyar intensified rainfall, strong winds, and high waves in Aceh, North Sumatra, West Sumatra, Riau, and nearby areas before dissipating.

Its prolonged downpours left steep, saturated terrain highly vulnerable to disasters, he said.

Meteorologists said the recent extreme weather across South-East Asia could have stemmed from the interaction of Typhoon Koto in the Philippines and Cyclone Senyar in the Malacca Strait.

Millions affected by floods in Thailand

The Thai government said 162 people had been killed by floods across eight southern provinces.

It said a total of more than 3.5 million people had been affected.

In the southern city of Hat Yai, the hardest-hit part of Thailand, the rain had finally stopped on Friday.

Earlier in the week, Hat Yai received its highest single-day rainfall in 300 years — 335 millimetres.

Floodwaters were still ankle-deep, and many homes remained without electricity.

Some residents said they were spared the worst of the floods but were still suffering from their effects.

In neighbouring Malaysia, where two people have been confirmed dead, tropical storm Senyar made landfall around midnight and has since weakened.

Meteorological authorities are still bracing themselves for heavy rain and wind, and warned that rough seas could pose risks for small boats.

A total of 30,000 evacuees remain in shelters, down from more than 34,000 on Thursday.

Malaysia's foreign ministry said on Friday that it had already evacuated 1,459 Malaysian nationals stranded in more than 25 flood-hit hotels in Thailand, adding that it would work to rescue the remaining 300 still caught up in flood zones.

ABC/Wires