According to the Directorate of Revenue Intelligence (DRI), the contents of the container had been declared as “dried ray skin”.

A report by the Times of India said this was a tactic used by smugglers since India’s ban on the export of shark fins in 2015.

Quoting Sharafat Ali, a “kingpin” known to have hired shark hunters and who was arrested in the raids, the report said the fins would be sun-dried at a warehouse in Sewri, Maharashtra, for about a week.

“They would then be sent to Veraval in Gujarat for polishing and processing, after which they would be brought back to Sewri and sent to Chennai and some places in Kerala.

“At these points, the fins would be packaged, labelled as ‘dried ray skins’ and loaded into containers,” the source said.

Ali and three others were booked under India’s Customs Act and are currently at the Arthur Road jail.

The warehouse in Sewri was one of two locations raided by the DRI on Saturday and Sunday. The other location was a warehouse in Veraval, Gujarat. Both are owned by Global Impex Trading Company.

This comes a week after reports that Malaysian Maritime Enforcement Agency personnel had seized some five tonnes of marine life, including 230 live tiger sharks, from three foreign trawlers off Sabah.

KM Arau commanding officer Mohd Zawawi Abdullah said the marine life, including the tiger sharks, had been kept in modified water tanks on the boats.

All three boats were manned by Vietnamese crew. Those on board the first boat had no valid fishing licence while the other two crews had licences. Two of the crewmen did not have proper papers.

Zawawi said the fishermen were being questioned on whether they intended to harvest the sharks for their fins or other reasons since they kept the creatures alive.

The case is being investigated under the Fisheries Act 1985 and Wildlife Protection Act 1972.