Bangladesh police declared Thursday that rampant piracy in the Sundarbans was a thing of the past, crediting a gun buyback scheme for reducing crime and tiger poaching in the vast mangrove forest.

Police said more than 130 pirates operating in the forested delta region had surrendered their weapons and ammunition in exchange for cash, legal aid and mobile phones since the programme began just over a year ago.

The scheme had virtually eradicated the lawlessness once rife in the world's largest mangrove forest, a natural habitat for endangered Bengal tigers, said a spokesman for the Rapid Action Battalion (RAB) police unit.

‘Most of the areas in Sundarbans are now pirate-free,’ Mizanur Rahman Bhuiyan told AFP.

‘So far 132 pirates-turned-poachers from 12 groups have surrendered. They abducted fishermen and were engaged in wildlife poaching in the Sundarbans.’

The battalion had spent more than a decade cracking down on criminality in the dense mangrove forest, with 117 pirates killed and nearly 400 arrested in sweeps since 2004.

But the buyback scheme, introduced in May 2016, has proved more effective in tackling crime in the UNESCO world heritage site.

Nearly 250 guns and 12,500 rounds of ammunition had been handed over in exchange for legal assistance, cash, mobile phones, winter clothing and gifts to mark the Islamic festival of Eid, Bhuiyan said.

The pirates are not granted amnesty for their offences but are viewed favourably for turning themselves in.

Home Minister Asaduzzaman Khan awarded each of the surrendered pirates $2,000 at a ceremony in the coastal town of Bagerhat on Wednesday, the RAB said.

Conservationists said the surrender of so many pirates represented a small victory for Bengal tigers, prize targets for poachers.

‘They kill tigers and deer indiscriminately. They poach tigers and sell their meat and body parts to people connected with the illegal wildlife trade,’ Anwarul Islam, a zoology professor at Dhaka University, told AFP.

The Sundarbans, which also straddle parts of eastern India, are home to rare wildlife including Irrawaddy dolphins and Bengal tigers -- both of which are endangered species due to poaching and habitat encroachment.

The big cat population in the 10,000 square-kilometre (3,861 sq mile) forest dropped to just over 100 in 2015 from an estimated 440 a decade earlier.

A UN agency last year urged Bangladesh's government to halt construction of a huge power plant at the edge of the forest, warning the controversial project could ‘irreversibly damage’ the Sundarbans.