Kolkata: A rise in tiger attacks in the Sundarbans mangrove forests of India indicates that the big cats are crossing over from Bangladesh where Cyclone Sidr destroyed much of their habitat, say wildlife activists in West Bengal.

"A large number of tigers and crocodiles have entered into India's side of the Sundarbans after being flushed out by Cyclone Sidr that ravaged Bangladesh in November last year," said Debasis Chakraborty, wildlife crusader and People for Animals (PFA) managing trustee.

"A vast area of mangrove forests was affected by that natural disaster leading to a serious displacement of wild animals."

He said a fisherman, Putul Naskar, was dragged away by a tiger at Benipheli forest in the Sundarbans on Sunday morning when he was busy catching crabs from the river.

"This was the ninth tiger attack in the Sundarbans since December last year and the sixth in the monsoon season. The tigers from Bangladesh side crossed the water channel and entered the Sundarbans in West Bengal through the Jhilla point in search of food.

"These tigers are not familiar with the human habitation and are attacking people very frequently," Chakraborty said.

The Sundarbans has a vast area covering 4,262 sq km, including a mangrove cover of 2,125 sq km, in India alone. A larger portion lies in Bangladesh.

Cyclone Sidr in the Bay of Bengal left behind a trail of devastation last year killing over 3,000 people and uprooting a large area of the mangrove forests in Bangladesh.

West Bengal Sundarbans Affairs Minister Kanti Ganguly said: "A good number of tigers might have come to this [India] side in search of food. They are also attacking people living in the deltaic region."

Chakraborty said: "We request all villagers of the Sundarbans not to go out for fishing and collect forest products inside the core area during monsoon, though it's regarded as off-season for tiger attacks.

"This is their [tigers'] mating season and they prefer to stay inside the dense forest area. But because of big cat infiltration from Bangladesh the tiger concentration has increased in the Sundarbans bio-sphere," Chakraborty said.

According to reports, an 18-year-old fisherman, Narayan Das, was mauled to death at Kultali in the Sunderbans a few weeks ago. In another incident, a tiger attacked 45-year-old Jangal Pramanik in Kultali when he was out with a fishing team in the Surjyamoni canal. A tiger suddenly pounced on Pramanik and injured him severely. When other fishermen raised an alarm, the tiger ran away. A 45-year-old woman was killed in a crocodile attack while catching crabs last week.