A worker at Defence PSU GRSE Ltd went missing in the Hooghly river here on Saturday during movement of a dredger boat, an official said.
Efforts are on to rescue the worker, who was working on a contractual basis on behalf of a contractor, the official said.
Rescue operations using in-house diving services of Garden Reach Shipbuilders and Engineers (GRSE) commenced immediately after the accident.
Assistance has also been sought from the Kolkata Port Trust, the Kolkata River Police and the NDRF, the official said.
The GRSE is a premier defence shipyards which primarily manufactures naval ships.