A strong cyclone is moving towards India and Bangladesh as authorities try to evacuate millions of people while maintaining social distancing.

Amphan is expected to make landfall on Wednesday morning, and forecasters warned of extensive damage from high winds, heavy rainfall, tidal waves and some flooding in crowded cities such as Kolkata.

The cyclone had winds of 136-142mph and is forecast to weaken before landfall around India’s West Bengal state and Bangladesh.

It is the second super cyclone on record that has formed over the Bay of Bengal, said India’s meteorological chief. The first of that classification was the devastating 1999 cyclone in Odisha state that left nearly 10,000 dead.

“This type of cyclone can be disastrous… It is completely unsafe,” said Mrutyunjay Mohapatra.

Amphan’s winds are whirling 435 miles from its eye as it approaches land. It is forecast to pass between the seaside resort town of Digha in India’s West Bengal state and Hatiya Island in Bangladesh with a weaker wind speed of 102-108mph.

Several districts of West Bengal will be most impacted by the storm, said Mr Mohapatra, warning of uprooted trees and electric poles and damage to old or temporary housing.

Flooding was a risk in Kolkata due to crowding and poor drainage and the storm surge would raise river levels in the Bengal delta, he said.

The Meteorological Department in Bangladesh said the cyclone could flood vast areas in south=western and southern Bangladesh from tidal waves up to five feet higher than normal, along with heavy rainfall and high wind speeds.

Fishing trawlers and boats in the Bay of Bengal have been asked to take shelter until further notice.