The enquiry committee formed by the city corporation has not found any evidence of sabotage behind the inferno in the capital's Banga Bazar.
The committee said either mosquito coil or cigarette smoke caused the fire which originated from an embroidery tailoring shop on the third floor of Adarsha market at Banga Bazar complex.
The inferno burned 3,845 shops to the ground, causing losses worth more than Tk 2.88 billion.
The committee submitted the report to the mayor of Dhaka South City Corporation (DSCC), Sheikh Fazle Nur Taposh on Tuesday evening.
The DSCC spokesperson confirmed the matter to the media.
According to the probe report, the committee interviewed six security guards and an electrician while investigating the incident.
The fire originated from the embroidery tailoring shop, owned by Alamgir, on the third floor of Adarsha market. The security guards would stay on the fourth floor right above the tailor's.
Billal Hossain, 60, the security guard of Adarsha market, said he noticed the flame coming out from inside of the closed tailoring shop while examining the lock system of all shops around 5:40 am -- a time when he screamed ‘fire, fire’.
Hearing his scream, the security guard, Delwar, and the electrician, Mamun, who were on the fourth floor, rushed to the spot. Then the trio tried to douse the fire with fire extinguishers.
Moments later, other people from nearby came to the scene to tame the blaze. The vehicles of the fire service reached the scene within 10 minutes of being informed by the security guards. But by that time the fire spread to the different parts of the market.