India will bring in and prosecute 35 Somali pirates its navy captured on a hijacked ship off Somalia, a navy official said, in a departure from its recent practice of rescuing vessels and crew but leaving the disarmed pirates at sea.

The captured pirates are due to arrive in India on Saturday and will be handed over to the law enforcement agencies, the official said. He declined to be identified as he was not authorised to speak to the media.

The exact charges against the pirates were not immediately clear, he added.

Indian navy commandos managed to release the Malta-flagged commercial ship MV Ruen on Saturday, which had been hijacked 450 nautical miles east of Socotra in the northern Arabian Sea by Somali pirates on Dec 14.

It marked the first hijacking of a merchant ship by Somali pirates since 2017. At the peak of their attacks in 2011, Somali pirates cost the global economy an estimated $7 billion, including hundreds of millions of dollars in ransom payments.

During the piracy peak, India's navy used to prosecute and jail in India pirates involved in major attacks, but in recent months the navy has taken to leaving the pirates at sea. The Ruen pirates will be the first India prosecutes in years, the official added.

India has deployed at least a dozen warships in the Gulf of Aden and the northern Arabian Sea since December, which enables it to assist vessels east of the Red Sea, where the navies of several countries, including the United States, are trying to secure shipping routes under attack from Yemen's Houthi militants.

The Indian official said that since the Ruen's hijacking, the navy has kept the region under "continuous surveillance activities" using its aerial platforms and information gathered from other vessels it has been investigating.

On March 14 Ruen was spotted off the Somali coast, British maritime security firm Ambrey said.

The navy official said that the pirates had converted Ruen into a mother-ship, using boats to launch attacks on other vessels. It was intercepted on March 15, the navy said in a statement on Saturday.

Another merchant vessel, MV Abdullah was hijacked off Somalia last week, and Somali forces were planning to attack with foreign navies.