A gas line underneath the mosque at Fatullah in Narayanganj caused the blast resulting in the death of 31 people, said a report of Titas.
Titas Gas probe committee submitted its report to the ministry concerned on Thursday blaming illegal gas connection for the incident.
In its findings, the probe body said the mosque was constructed on an abandoned gas line without informing Titas.
Around 31 devotees, who received burn due to the mosque blast on September 4, succumbed to injuries so far.