"...global warming has started to show its far-reaching effects here," said Pranabes Sanyal, the eastern India representative of the National Coastal Zone Management Authority (NCZMA).

"Many towns and cities along the coast will be devastated by the changing climate in coming years."

Millions live along India's 3,700 km (2,300 mile) eastern coast and remain vulnerable to storms, flooding and tsunamis. The 2004 Indian Ocean tsunami killed some 230,000 people, around 16,000 of them in India.

Sanyal said the wind speed of cyclones hitting the eastern states of Andhra Pradesh and Orissa had almost doubled to 250 km (155 miles) per hour from 150 km (90 miles) per hour in 2000.

In addition, sea levels in some parts of the Bay of Bengal were rising at 3.14 mm annually against a global average of 2 mm, threatening the low-lying areas of eastern India.

Water levels off the coast of Khulna in Bangladesh were rising at an even higher rate of 10 mm every year, Sanyal added.

NCZMA officials say rising sea levels are eroding one metre (3.2 feet) of land every year along the coast of West Bengal state, inundating more and more coastal areas every year and leaving them "highly vulnerable".