Authorities have already moved more than 1.2 million people to relief camps.

The southern tourist hotspot of Kerala, which was hit by its worst floods in almost a century last year leaving 450 dead, was once again bearing the brunt of monsoon downpours.

"The death toll in the state has increased to 88... and there are still at least 40 people missing," Pramod Kumar, Kerala police spokesman, told AFP.

More than 250,000 people across the state's worst-affected districts including Wayanad, Malappuram and Kozhikode have been shifted to relief camps.

At least 48 people have also lost their lives in neighbouring Karnataka state.

A state government official told AFP that 16 people were still missing in Karnataka but the situation had improved as rains had eased.

"We have rescued around 677,000 people in the last few days and think the water level will start dropping in another 24-48 hours," the official said.

Local emergency personnel and troops from the army, navy and air force have been deployed for search, rescue and relief operations.

Indian media have also reported 66 deaths in the western states of Gujarat and Maharashtra, with hundreds of thousands rescued from inundated regions.

The monsoon rains are crucial to replenishing water supplies in drought-stricken India, but they kill hundreds of people across the country every year.