New Delhi: The Merchant ship MV Chem Pluto which was attacked two days ago by a drone arrived outside the Mumbai port under the protection of Indian Coast Guard ship Vikram, Defence officials said on Tuesday.

The cargo of the ship is planned to be transferred to another ship and a joint investigation is being carried out by the Indian Coast Guard, Indian Navy, Intelligence agencies and other officials concerned to ascertain how the ship was attacked on December 23.

As per the defence officials, the agencies would also try to find out whether the projectile used to attack the ship was a missile or a drone. The Indian Coast Guard has also enhanced patrolling in the area to protect merchant vessels passing in the region.

The officials said on Sunday that the India-bound merchant vessel, 'which came under attack by a drone', is being escorted back to native shores by Coast Guard ship Vikram in the Arabian Sea.

According to officials, the merchant ship, hit by a suspected drone, requested to be escorted by the ICGS Vikram.

Indian Coast Guard Dorniers are also airborne to keep an eye on the merchant vessels and carry out surveillance in the area, officials added.

MV Chem Pluto, with 20 Indian and one Vietnamese crew member on Saturday caught fire after it was attacked by a suspected drone. It was later secured by the Indian Coast Guard (ICG), the ICG said in an official statement.

The merchant vessel reportedly commenced its voyage from the UAE on December 19 and was bound for New Mangalore port with an arrival date of December 25.

According to the official statement, on December 23, the Indian Coast Guard Maritime Rescue Coordination Centre in Mumbai received information regarding a fire onboard MV Chem Pluto, reportedly attacked by a suspected drone strike or aerial platform.

The Indian Coast Guard Maritime Coordination Centre (MRCC), which established real-time communication with the vessel's agent, ascertained no loss of life and assured all assistance.

It was also learned that the vessel fire had been doused by the crew. To augment the vessel's safety, MRCC Mumbai has activated ISN and immediately diverted other merchant vessels in the vicinity of Chem Pluto for assistance.

"The Indian Coast Guard also pressed Offshore Patrol vessel Vikram and Coast Guard Dornier maritime surveillance aircraft into action for rendering assistance to Chem Pluto. The Coast Guard Dornier aircraft has sanitised the area and established communication with Chem Pluto. The vessel has started making its way towards Mumbai after undertaking damage assessment and repairs on its power generation systems," the statement further read.