DHAKA (AFP) - Pirates in southeastern Bangladesh are believed to have killed at least 16 fishermen by tying them up and throwing them into the Bay of Bengal to drown, police said on Monday.

Police said a fishing boat at Kutubdia Island in Cox's Bazaar resort district recovered three bodies after fishermen found them floating in the sea and at least 13 other bodies had been seen.

"They have recovered three bodies with their hands and feet tied with rope and brought them to shore," local deputy police chief Imran Bhuiyan told AFP.

"Fishermen told us they have seen at least 16 bodies floating in the sea," he added, saying the bodies had no injury marks.

"We believe that the pirates threw them into the sea alive," he said.

Fishermen were helping in the police operation to recover the other bodies.

The pirates were thought to have killed the fishermen to steal the engine, fishing nets and catch of the boat on which they were working, deputy police chief Bhuiyan said.

Pirates routinely rob, kidnap and extort money from fishermen working along the coastline and attempts by naval and air forces to crack down on criminal activity at sea have proved futile.

Last August, Bangladeshi authorities said they had rescued at least 60 fishermen abducted by pirates in the Bay of Bengal.