Bangladesh has only about 100 tigers living in the world's largest mangrove forest, far fewer of the endangered animals than previously thought, following a recent survey, a top forestry official said Monday.

Some 440 tigers were recorded during the previous census conducted in 2004 in the World Heritage-listed Sundarbans, one of the world's last remaining habitats for the big cats.

But experts said better methodology was the reason for the huge drop in the numbers, saying hidden cameras used this time around, rather than pug marks, gave a much more accurate figure.

Tapan Kumar Dey, the government's wildlife conservator, said analysis of camera footage from the year-long survey that ended in April found numbers ranged between 83 and 130, giving an average of 106.

"So plus or minus we have around 106 tigers in our parts of the Sundarbans. It's a more accurate figure," Dey told AFP of the survey, which has not yet been publicly released.

About 74 tigers have previously been counted on the Indian side of the Sundarbans, which makes up nearly 40 percent of the forest straddling both countries over 10,000 square kilometres (3,860 square miles).

Bengal tigers live mainly in India, where nationwide there are 2,226, with smaller populations in Bangladesh, Nepal, Bhutan, China and Myanmar.

Monirul Khan, a zoology professor at Bangladesh's Jahangirnagar University and the nation's foremost tiger expert, said the new survey confirmed his worst fears.

"It seems the population has declined (in the past) to more than what we had feared," Khan said, saying his studies showed the figure was no more than 200.

Khan said the government needed to do more to protect the animals, whose numbers were shrinking because of poaching and rapid development on the edge of the forest.

The World Wildlife Fund says tigers worldwide are in serious danger of becoming extinct in the wild. Their numbers have fallen from 100,000 in 1900 to around 3,200 now.

Officials have conceded that the pugmark tracking system used in 2004 was unreliable and cameras were installed in trees throughout the forest for the latest survey.

YV Jhala, professor at the Wildlife Institute of India, told AFP the new figure was the "reality".

"The 440 figure was a myth and an imagination. Bangladesh parts of the Sundarbans with its prey size can support up to 200 tigers," he said, also urging authorities to act to better protect the cats.