This is the heroic moment marine officers removed a cable stuck around a dolphin's body.

Staff of Thailand's Marine and Coastal Resources Department were out on patrol off the coast of Trang province on February 15 when they spotted the two-metre-long humpback dolphin thrashing in the water. Its tail had become ensnared in a length of discarded rope, leaving it unable to swim freely.

Footage shows how the men cut the cable using a small knife while the sea creature struggled to break loose. Despite suffering a one-centimetre-deep wound at the base of its tail, the marine mammal was still able to swim and breathe normally, the rescuers said.

Fishermen in the area also told them the rope was being used to catch crabs.

The marine officers have reportedly coordinated with local and marine life preservation authorities to monitor the dolphin as it heals.