Earlier, on 24 December, the shipping ministry formed the seven-member probe committee, asking it to submit its report within three working days. But the deadline was missed.
As per the appeal of the committee, three more working days have been granted, said a notification issued by the ministry.
Joint secretary of the shipping ministry Tofayel Ahmed is the convener of the committee while deputy secretary Aminur Rahman is its member secretary.
Coast Guard members and fire fighters have been continuing searching the river for bodies.
According to a list of the missing people compiled by the Jhalakathi office of the Red Crescent Society, at least 58 people are still missing.
Meanwhile, an FIR was lodged at Jhalakathi police station on Monday night, following a complaint from the victims’ side, accusing eight people, including launch co-owner Hamjalal Sheikh, for the tragedy.
A team of Rapid Action Battalion (RAB) arrested Hamjalal in connection with the deadly fire. His arrest followed the Dhaka Marine Court’s warrants for the arrest of four owners and four staff of the launch in a case filed by the department of shipping.
The blaze broke out around 3:00am on 24 December on the Barguna-bound launch carrying some 800 passengers from Dhaka and it engulfed the entire vessel within 10 minutes.