India and Bangladesh are evacuating millions of people from coastal areas ahead of what could be the biggest cyclone in more than two decades.

However, coronavirus precautions and India's lockdown are hampering efforts.

Cyclone Amphan currently has wind speeds of around 140mph, though they are expected to weaken before it makes landfall on the border between India and Bangladesh on Wednesday, bringing heavy rainfall too

Amphan is the most intense and second super cyclone after the 1999 Odisha cyclone which left almost 10,000 dead.

“We are dealing with a multi-hazard scenario, extensive damage is expected, no one should be outside, people in low lying areas are to be evacuated,” said India's meteorological chief Mrutyunjay Mohapatra.

“We are utilising all tools and technologies to monitor it,” he further added.

Mr Mohaptra also said flooding was a danger in Kolkata, a city of almost 15 million, due to its dense population, poor drainage and the fact that Amphan's storm surge could raise river levels in the Bengal delta.

It is feared Amphan will cause large scale and extensive damage to coastal areas.

India has deployed about 25 teams from the National Disaster Response Force (NDRF) to raise awareness of the cyclone and begin evacuations.

Another 12 teams are on standby should they be needed.

“For the first time we are having to face two disasters simultaneously, we are facing a dual challenge of the cyclone in the time of Covid-19," Satya Narayan Pradhan, head of India’s National Disaster Response Force, said.

“We are taking action according to the enormity of this challenge."

Last year, Cyclone Fani hit Odisha in May, killing more than 70 people in Odisha and West Bengal.

Fani was also an Extremely Severe Cyclonic Storm with maximum sustained wind speeds of 135 mph.

In neighbouring Bangladesh, 2.2 million people are being evacuated from coastal districts, State Minister for Disaster Management Enamur Rahman said at a media briefing in Dhaka.

The country plans to raise the danger signal to the maximum level at 6am on Wednesday and said after this it will be impossible to evacuate people after this.