The body of a man was found in the tunnel of Kolkata Metro's Blue Line in the early hours of Friday, officials said.
The body was found between the Park Street and Esplanade stations during the inspection of the line by the metro's engineering staff after the service hours, around 2.15 am, they said.
"The New Market police station was informed after the body was spotted. Police recovered the body and sent it for post-mortem examination," an official said.
The man, believed to be around 35, is yet to be identified, police said.
It is being investigated how the man reached the middle of the tunnel evading detection, officials said.
Efforts were being made to identify the man, they said, adding that his photo has been shared with all police stations in Kolkata and the nearby districts.
The incident did not affect morning services on the Blue Line, which connects Dakshineswar to the Sahid Khudiram station near Garia.