Though the grenade was recovered on Wednesday, police made the disclosure on Thursday.
Helal Uddin Faruki, inspector (investigation) of Jorarganj Police Station, said that on information from BSRM factory, a team of police went to the spot.
They spotted the grenade in iron rod making raw materials.
Later, a bomb disposal unit from CTU defused the bomb.
A general diary has been filed in this connection, said the inspector adding that they are investigating the incident.