Troops in Sri Lanka were racing to rescue hundreds of people marooned by rising flood waters on Friday as weather-related deaths rose to 69, with another 34 people declared missing.

Helicopters and navy boats carried out rescue operations, plucking people from treetops, roofs and villages cut off by flood waters.

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 360mm in the past 24 hours, the DMC said. The Kelani River, which runs into the Indian Ocean near the capital Colombo, overflowed its banks on Friday.

VSA Ratnayake, 56, said he had to leave his flooded home in Kaduwela, near Colombo. “I think this could be the worst flood in our area for three decades,” Ratnayake said. “I remember a flood in the 1990s when my house was under 7ft of water.”

Kalyani, 48, also from Kaduwela, said she was sheltering two families whose homes were flooded.

People leave their homes in Wellampitiya, near Colombo. Photograph: Tharaka Basnayaka/NurPhoto/Shutterstock

At least 3,000 homes were damaged in mudslides and floods, and more than 18,000 people have been moved to temporary shelters. In Anuradhapura district in the north, a 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.

India’s prime minister, Narendra Modi, expressed his condolences over the loss of life in Sri Lanka and said Delhi was rushing out aid to the affected areas. “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. Dozens of stranded tourists were evacuated to Colombo from the tea-growing central areas on Friday.

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.

Sri Lanka is in its north-east 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 owing to the climate crisis.

This week’s weather-related toll is the highest since June last year, when 26 people were killed during 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.