The fire was caused by an explosion in the boiler room of the factory in Tongi, just north of the capital Dhaka.
At least 23 people have been killed and 70 injured in a huge fire at a packaging factory in Bangladesh on Saturday.
Around 100 people were working at the building when flames tore through it following an explosion in the boiler room of the four-storey factory in the industrial town of Tongi, just north of the capital Dhaka.
Factory inspection department head Syed Ahmed confirmed the death toll had risen to 23 following the incident at the factory, which supplies foreign and domestic brands.
"We still have not controlled the blaze and we fear some workers are still trapped in the factory," police inspector Aminul Islam told AFP.
Parvez Mia, a doctor at the Tongi government hospital, told AFP at least 70 people were injured, many critically.
Chemicals may have been stored on the ground floor of the factory, helping to explain how the blaze that began at 6 am (0000 GMT) spread so fast, said Tahmidul Islam of Bangladesh's industrial police unit.
"What we have heard is that there were chemical stored on the ground floor. As a result, the fire took no time to spread," Islam told AFP, adding scores of fire officials were still battling to bring the blaze under control.
The factory produced and printed the plastic packaging for food items like potato chips and small household goods including mosquito coils.
Fires and other accidents are common in the factories that make up the $27-billion garment industry in Bangladesh, the world's second-biggest apparel exporter after China.
In November 2012, at least 111 workers were killed when a devastating fire engulfed a nine-storey garment factory in the Ashulia industrial area, outside the capital Dhaka.
The accident was followed by an even bigger tragedy six months later when 1,138 people died after another clothing factory complex collapsed, trapping over 3,000 workers.
Western brands subsequently upgraded safety standards and inspections for suppliers, dramatically reducing incidents of fire and other accidents at export-orientated factories.