Photographs taken by a coastguard plane showed a thick plume of billowing black smoke and containers that had been seemingly hurled up by a powerful explosion on board.

"Fire incident reported onboard Singapore-flagged container vessel MV Wan Hai 503," India's defence ministry said in a statement, adding it had diverted a destroyer to aid the stricken boat.

It said the 268-metre (879-foot) vessel caught fire some 78 nautical miles off Beypore port.

It did not give details of any rescue, but broadcaster NDTV reported that 18 of the 22 crew members had left the ship, citing an unnamed navy official.

Last month a Liberian-flagged container ship with hazardous cargo sunk off the coast of Kerala. The Indian navy rescued all 24 crew members.