In the worst hit state, Orissa, Chief Minister Giridhar Gamag said: "You cannot imagine the devastation."

"The deaths will not be in tens, but in hundreds," he said.

BBC's Daniel Lak: Thousands of emergency specialists have been deployed

Air force helicopters have been called into action on Saturday, dropping food parcels to the worst hit areas.

Rescuers also plan to distribute food, vaccines and polyethylene sheets to cyclone victims.

More than 100,000 houses have been damaged and 50,000 people evacuated from nine coastal villages.

The rescue operation is beginning

But rescue efforts are being hampered by continuing bad weather. All telephone communications are down and road, rail and air links have also been cut.

India's meteorological office officially classified Storm O5B as a supercyclone - with wind speeds of over 250km/h (160 mph).

Missing at sea

So far, only two deaths have been confirmed but that number is expected to rise rapidly.

Many towns and villages have not been able to report casualty figures or damage assessments because of downed telephone lines.

At least 200 fisherman have been reported missing, and 4,000 others are believed to be stranded at sea.

The cyclone ripped through the port town of Paradwip, then moved on to Bhubaneswar, the state capital 90km (55 miles) from the coast.

An official said the port and parts of the town had been "extensively damaged".

United News of India reported that the West Bengal state government had decided to evacuate nearly 200,000 people from islands in the Bay of Bengal.

Bangladesh evacuation

A similar storm hit the area less than two weeks ago, killing more than 150 people and affecting nearly 500,000 others.

On Thursday, neighbouring Bangladesh placed 33,000 volunteers on alert and began evacuating residents of south-eastern Khulna and Barguna coastal districts to concrete shelters.

Bangladeshi weather officials said the storm could hit the country's main Chittagong port and Cox's Bazar resort district.

The Sundarbans forest, home to 362 famous Royal Bengal tigers, is in the path of the storm.

Bangladesh is lashed by cyclones and floods every year. A devastating cyclone in 1991 claimed 139,000 lives.