Intense overnight storms which deposited 300 millimetres (12 inches) of rain have left rivers in spate in the mountainous district in the eastern state of West Bengal, causing widespread damage.

Raging waters have smashed into bridges and caved in roads.

"In the wake of last night's heavy cyclone in the Darjeeling hills, over 20 people have lost their lives," said Harsh Vardhan Shringla, a lawmaker in India's upper house.

Prime Minister Narendra Modi said he was "pained by the loss of lives".

"The situation in Darjeeling and surrounding areas is being closely monitored in the wake of heavy rains and landslides," he said in a statement on social media.

West Bengal Chief Minister Mamata Banerjee said several areas "have been flooded due to sudden huge rains within a few hours last night as well as due to rush of excessive river water".

"Two iron bridges have collapsed, several roads have been damaged and flooded, and huge tracts of land have been inundated," Banerjee said on X.

Floods and landslides are common during the monsoon season in the subcontinent, but experts say climate change, coupled with poorly planned development, is increasing their frequency, severity and impact.