The Karachi-bound cargo vessel from Bangladesh carrying military hardware and explosives was kept cordoned off on Saturday at Diamond Harbour in South 24 Parganas district with the captain disembarked and taken for questioning.
The captain of the Liberian registered ship, who was not identified, was taken to the Radisson Fort resort for questioning, police officials said.
The Navy and Coast Guard personnel had seized the ship on Friday on an intelligence tip off. It was anchored at Kalicharanpara.
The police and the Customs were still present on the ship, M V Agean Glory. The name of the ship had been given as S G Zyat last night by the officials.
It had set sail from Chittangong in Bangladesh and had anti-aircraft guns, rocket launchers, five tonne of explosives, besides a huge quantity of ammunition and smoke bombs in two large containers on board.
Director General of Police Bhupinder Singh had described the incident as “alarming” and said it was surprising why the Pakistani-bound vessel was passing through Indian waters.