Bangladeshi police are hunting a factory boss after claims that workers were told that an alarm for the deadly fire was a routine drill.
Dhaka police chief Habibur Rahman said officers wanted to question Tazreen's owner, Delwar Hossain, about building rules after inspectors found the nine-storey factory had permission for only three floors.
"We shall also quiz him about allegations from survivors that his managers did not allow the workers to leave the factory when the fire broke out," Mr Rahman said. "As the smoke spread, the managers even told the workers that it was a fire drill, nothing to be afraid of."
Police have opened a murder docket, Rahman added. "We have launched a search for him and the managers but so far we have not been able to trace them."