Pirates are thought to have killed 16 fishermen off the coast of Bangladesh by tying them up and throwing them into the Bay of Bengal.

The fishermen's hands and feet were bound before they were thrown into the bay to drown.

Thirteen of the bodies were seen floating in the water off Kutubdia Island and a fishing boat recovered the other three.

"Fishermen told us they have seen at least 16 bodies floating in the sea," local deputy police chief Imran Bhuiyan told Agence France-Presse, adding that the bodies had no injury marks.

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

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Other fishermen were helping the police recover the bodies.

Police chief of Cox's Bazaar Mohammad Azad Mia said 23 fishermen had gone missing a couple days prior to the bodies surfacing after sailing out from Kutubdia Island about a week before. He said they have no information about the other seven fishermen who are still missing.

The pirates were thought to have wanted to steal the engine, fishing nets and catch of the boat where they killed the fishermen.

Last August, Bangladesh launched a joint air and naval operation in the Bay of Bengal after 50 fishermen were kidnapped by pirates armed with sophisticated weapons.

Murder is rare, but abductions for ransom do occur occasionally along the Bangladesh coast, where hundreds of thousands of fishermen work throughout the year.