Dozens of crocodiles bred in captivity in eastern India have been enlisted to protect their endangered counterparts in the wild and are being released in forests to scare away poachers, authorities said on Monday.

Illegal fishing in mangrove forests and habitat destruction in the states of Orissa and West Bengal had led to a steep fall in crocodile numbers, from several thousand a century ago to less than 100 in the early 1970s, they said.

But the same reptiles were breeding rapidly in captivity. Orissa's Bhitarkanika sanctuary has more than 1,400 crocodiles now.

"The swelling number of released crocodiles in the wild is working as a deterrent and keeping people away from the mangrove as villagers are more cautious before venturing into the forests," said Rathin Banerjee, a senior wildlife official.

Wildlife sanctuaries in the region are threatened by poachers and villagers foraging for wood and forest produce.

But large crocodiles leaping out of the water to attack prey or capsize boats and canoes were proving to be a good weapon, said Banerjee, a crocodile breeding expert.

Last year, a 23 foot (7 metres) estuarine crocodile in Bhitarkanika entered the Guinness Book of World Records as the world's largest.

Three other estuarine crocodiles at the sanctuary, all measuring more than 19 ft, have also found a mention on the Guinness Web site.

"Unlike guard dogs, crocodiles cannot be tamed and are ferocious and can attack anyone in the swamps," said Banerjee.