An Indian warship on patrol in the western Arabian Sea was on Friday fired upon by Somali pirates on board a merchant vessel (MV) hijacked by them three months ago, an attack that saw the Indian Navy respond in self-defence and later forced the pirates to surrender and free the hostages held by them, the navy said on Saturday.

The action lasted 40 hours and involved the elite marine commandos being air-dropped by C-17 aircraft.

MV Ruen was hijacked by the pirates on Thursday and was since being used by them as a pirate ship to target vessels on the high seas. That incident took place 700 nautical miles from the Indian coast.

“The vessel opened fire on the warship, which is taking actions under international law, in self-defence and to counter piracy; with minimal force necessary to neutralise the pirates’ threat to shipping and seafarers,” the navy said in a statement.

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INS Kolkata, in the last 40 hours, through concerted actions successfully cornered and coerced all 35 pirates to surrender and ensured safe evacuation of 17 crew members on Saturday evening from the pirate vessel without any injury, the navy said in another statement.

INS Kolkata intercepted the pirate ship Ruen almost 1400 nm (2600km) from the Indian Coast and “forced it to stop through calibrated actions which were augmented by INS Subhadra, RPA (remotely piloted aircraft), P8-I maritime patrol aircraft & marine commandos air-dropped by C-17 aircraft.”

The vessel was sanitised for illegal arms, ammunition and contraband, the statement added.

The navy has stepped up surveillance in the Arabian Sea substantially and deployed task groups consisting of several warships in the face of rising threats in the area, including the recent attacks on India-bound merchant vessels and the resurgence of piracy.

The navy has thwarted several piracy attempts in and around Arabian Sea in the last few months and responded to distress calls made by merchant ships hit by missiles and drones launched by Iran-backed Houthi rebels.