Mongla Port Authority Harbour Master Mohammad Waliullah said the ship named MV Bilash sank in the Harbaria area around 3am on Monday.
No casualties have been reported. The vessel ran aground on a sandbar nearly 60 nautical miles from the port at Harbaria-5, said Waliullah.
The lighter vessel then ran aground on a sand bar in the Harbaria area. The crew contacted the port for help, but by the time help arrived strong tides had overturned the vessel.
The coal load was not released and there is no concern of an environmental disaster, claims Sahara Enterprise.
According to Harbour Master Walimullah the MV Shipsha was sent to the location to try and rescue the MV Bilash, but the tides overturned the hip around 3am and caused it to sink.
Parts of the lighter ship are still visible and recovery operations are ongoing, he said.