A home ministry probe body formed after the Chawkbazar fire concluded that the flames originated from the first floor of Wahed Mansion.
But a forensic examination by experts may be able to find the exact cause of the fire, officials said.
The five-member investigation committee submitted to Home Minister Asaduzzaman Khan Kamal its report with recommendations to prevent future disasters.
“The fire was originated at a chemical godown on the first floor of Wahed Mansion in Chawkbazar's Churihatta. The fire spread from there and turned devastating through an explosion,” said the report submitted on Thursday.
At least two other probes also came to similar conclusions earlier.
The fire on February 20 claimed the lives of at least 71 people and injured many others.
At least four committees were formed after the fire.
Home ministry's report said forensic experts would probably be able to tell what kind of chemical or gas was stored on the first floor of the building.
Its short-term recommendations included preparing a list of factories and warehouses of chemical, plastic, polythene, battery, shoes, counterfeit medicines, fake cosmetics and other flammable substances.
It also recommended identifying as soon as possible the very risky and low-risk areas considering the population density and number of factories and warehouses.
Its recommendations to be implemented in the long run included taking initiatives to move those establishments out of the residential areas and to conduct regular mobile court drives.
There should be hydrant points and water reservoirs in the area to douse any future fires.
Obtaining a licence for a chemical warehouse or factory should require a No-Objection-Certificate from the fire service, it said.
It should be mandatory to appoint trained and efficient chemists in the warehouses.
No high-rise building should be constructed near chemical warehouses and factories, it suggested, adding that such establishments should not be set up within 10 metres of any educational or religious institutions and community centres.
The report mentioned that the Old Dhaka roads should be widened for vehicles of fire service and other emergency responders. Redevelopment the old town with modern facilities is needed. Vehicular movement can be prohibited on the narrow roads.
IEB PROBE REPORT
Officials of the Institution of Engineers who are also investigating the fire earlier said the fire broke out at Wahed Mansion due to the chemical storage. They ruled out the explosion of a gas cylinders as the source of the fire.
Khandker Manjur Morhsed, general secretary of the institution, told The Daily Star that the fire could have originated from the spark of a gaslight or match. “We recommended a forensic examination to find out the exact cause.”
They submitted their report to Prime Minister Sheikh Hasina on March 1.
EXPLOSIVES DEPARTMENT REPORT
A probe of the Department of Explosives also found that the fire originated from the first floor of the building where perfume cans and gas lighters were stored.
“We prepared the report analysing the CCTV footages, witnesses' statements and examining the evidence. There were highly inflammable substances there, the fire originated from an explosion of one of those chemicals,” Samsul Alam, chief inspector of the department, told The Daily Star.
INDUSTRIES MINISTRY REPORT
A committee of the ministry submitted its report on Thursday, but the findings have been kept secret, an official said.