Bangladesh wildlife officials are mulling a ban on access to the Sundarbans after an alarming rise in poaching of tigers that live in the world's largest mangrove forest, rangers said Wednesday.

Five skins of endangered Royal Bengal tigers have been seized so far in 2015, compared to an average of one or two discovered in previous years, Sundarbans top ranger Jahir Uddin Ahmed said.

"It's an extremely alarming development," Ahmed told AFP.

Police shot dead six alleged poachers in a gunfight in the Sundarbans on Sunday and seized three skins along with tiger bones and other body parts.

Tiger meat and bones are used in traditional Chinese medicine and fetch high prices.

"We did not find any bullet marks in the skins of the tigers. We apprehend they were poisoned to death. We have to stop this at any cost," Ahmed said.

Forest officials said they were considering the ban in the 10,000-square-kilometre (3,850-square-mile) forest which straddles Bangladesh and India in a bid to halt the poaching.

Rapid Action Battalion seized a tiger skin, head and bones from Morrelganj upazila under Bagerhat district and arrested three people in this connection on January 13, 2015. STAR file photo

"It (access) should be stopped for the sake of tigers," said Jahidul Kabir, who is charged with looking after the UNESCO World-Heritage listed part of the forest.

"If this trend in poaching continues, there will not be a single tiger in the Sundarbans after ten years," Kabir told AFP.

Authorities fear poachers are hiding among the up to 6,000 locals who enter the forest everyday for their livelihoods, including to fish and collect wild honey.

Concern about the tigers spiked after officials said last month the number of big cats in the Sundarbans has nosedived to 106 from an estimated 440 a decade ago.

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