The death toll from floods across large swathes of Southeast Asia rose to at least 183 on Friday, with authorities in the region 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.

Another 46 people were killed by a cyclone in the South Asian island nation of Sri Lanka, authorities said.

On badly hit Sumatra in Indonesia, 94 people had been confirmed dead by Friday afternoon, according to data from three provincial authorities.

In the Padang Pariaman region of Sumatra, where a total of 22 people died, residents had to cope with water levels at least one metre high, and had still not been reached by search and rescue personnel on Friday.

"We're running out of supplies and food," said Muhammad Rais, a 40-year-old resident who was forced to move to the second floor of his home on Thursday to escape the rapidly rising waters.

Communications remained down in some parts of the island, and authorities were working to restore power and clear roads that have been blocked by landslide debris, he said.

Indonesia will continue to airlift aid and rescue personnel into stricken areas on Friday, he added.

The Thai government said in a statement that 87 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, but residents were still ankle-deep in flood waters and many remained without electricity as they assessed the damage done to their property over the last week. One said he had "lost everything".

In Malaysia, where two people have been confirmed dead, tropical storm Senyar made landfall at around midnight and has since weakened. Meteorological authorities are still bracing themselves for heavy rain and winds, 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 neighboring Thailand, adding that it would work to rescue the remaining 300 still caught up in flood zones.