Mumbai, Aug 15 (IANS) The Indian Navy says that the cargo ship it intercepted late Sunday may have been hijacked and used for smuggling contraband.

The 500-tonne M.V. Nafis-I had been drifting for the past 20 days in the Arabian Sea and had a crew of five Yemenis, two Tanzanians, one Somali and one Kenyan on board.

An official spokesperson said Monday the ship had been sighted moving suspiciously around 250 nautical miles in the Arabian Sea by an Indian Navy aircraft Aug 12 which alerted the shore authorities.

Coming barely four days before the country's Independence Day celebrations, the authorities swung into action and immediately placed the vessel under surveillance by a naval aircraft and the destroyer, INS Mysore, the official informed.

Late Sunday night, it was intercepted by INS Mysore at around 170 nautical miles off Mumbai coast.

Braving rough weather and upto 14 feet tall waves, the navy's elite Marine Commandoes (MARCOS) landed on the ship from two helicopters.

Taken by surprise, the crewmen offered no resistance and surrendered to the Indian authorities.

A search of the ship revealed an unspecified quantity of automatic weapons on board, the official said.

"This (Monday) morning, the intercepted ship is being towed to Porbander port in Gujarat. We are making further investigations into the ship's origins, its movements close to the Indian shores and also the crew," the official told IANS.

The ship and the crew members will be handed over to the local police and other agencies for further investigations and action, the official said.