Helicopters and navy boats carried out multiple rescue operations, plucking residents from tree tops, roofs and villages cut off by floodwaters.

The Disaster Management Centre (DMC) said the toll had climbed with the recovery of more bodies in the worst affected central region, where most victims had been buried alive as mudslides hit this week.

Rain was falling across the island with some regions receiving 360 millimetres in the past 24 hours, the DMC said.

The Kelani River, which flows into the Indian Ocean near the capital Colombo, breached its banks on Friday.

V. S. A. Ratnayake, 56, said he had to leave his flooded home in Kaduwela, just outside Colombo.

"I think this could be the worst flood in our area for three decades," Ratnayake told AFP. "I remember a flood in the 1990s when my house was under seven feet of water."

Another Kaduwela resident, Kalyani, 48, who uses only one name, said she was sheltering two families whose homes were flooded.

At least 3,000 homes were damaged in mudslides and floods, and over 18,000 people had been moved to temporary shelters.

In Anuradhapura district in the north, an Air Force Bell 212 helicopter airlifted a man who had climbed a coconut tree to escape rising waters.

The DMC said more rain was forecast, with Cyclone Ditwah likely to move away from the north towards the south Indian state of Tamil Nadu by Sunday.

- 'Nowhere to go' -

Indian Prime Minister Narendra Modi expressed his condolences over the loss of life in Sri Lanka and said New Delhi was rushing aid.

"We stand ready to provide more aid and assistance as the situation evolves," Modi said on X.

DMC officials said they expected flood levels to be worse than in 2016, when 71 people were killed nationwide.

The Sirasa TV network broadcast an appeal for help from a desperate woman.

"We are six people, including a one-and-a-half-year-old child. If the water rises another five steps up the staircase, we will have nowhere to go," she said by telephone.

Dozens of stranded tourists were evacuated to Colombo from the tea-growing central areas on Friday.

Sri Lanka is in its northeast monsoon season, but rainfall has intensified because of Cyclone Ditwah, the DMC said.

Sri Lanka depends on seasonal monsoon rains for irrigation and hydroelectricity, but experts have warned that the country faces more frequent floods due to climate change.

This week's weather-related toll is the highest since June last year, when 26 people were killed following heavy rains. In December, 17 people died in flooding and landslides.

The worst flooding Sri Lanka has experienced since the turn of the century occurred in June 2003, when 254 people were killed.