Rescuers have used helicopters and boats to evacuate thousands of people stranded on rooftops after unprecedented flooding in the southern Indian state of Kerala.

The flooding has killed more than 320 people in the past nine days, officials said.

With heavy rain stopping after a week, rescuers moved quickly to take those marooned by floods to 1,500 state-run camps, using more than a dozen helicopters and about 400 boats across the state.

The state’s top elected official, Pinarayi Vijayan, told reporters that at least 324 people had died and more than 220,000 had taken refuge in the camps.

People move past a flooded road in Thrissur
Thousands of people have been evacuated (AP)

Heavy rain over the past eight days triggered flooding, landslides and home and bridge collapses, severely disrupting air and train services in Kerala state, a popular tourist destination with scenic landscapes, waterfalls and beautiful beaches.

The New Delhi Television news channel reported that the state was facing a new crisis with some hospitals suffering shortages of oxygen and petrol stations running short of fuel.

Monsoon rains kill hundreds of people every year in India. The season runs from June to September.

The flooding has severely hit 12 of Kerala’s 14 districts, with thousands of homes damaged since June.

Crops on 80,300 acres of land have also been damaged, the Home Ministry said.

People move past a flooded area in Thrissu
The flooding has severely hit 12 of Kerala’s 14 districts (AP)

The international airport at Kochi, a major port city, suspended flight operations until Saturday after the runway was flooded.

Authorities also asked tourists to stay away from the popular hill station of Munnar in Idukki district because of flooding.

More than 1,000 people have died in seven states since the start of the monsoon season in June.

A total of 407 people have died in Kerala, 190 in Uttar Pradesh, 183 in West Bengal, 139 in Maharashtra, 52 in Gujarat, 45 in Assam and 11 in Nagaland state, officials and the Press Trust of India news agency reported.