Local police questioned the owner of the garment factory that caught fire late Saturday over speculations on possible violations of building rules and allowing poor working conditions.

Dhaka police chief Habibur Rahman said officers were interrogating factory owner Delwar Hossain after inspectors found the nine-storey building had planning permission for only three floors.

There were also allegations that the managers did not allow workers to leave the factory when the fire broke out.

“As the smoke spread, the managers even told workers that it was a fire drill, nothing to be afraid of,” Rahman told AFP.

The blaze swept through the Tazreen factory, leaving more than 100 people dead after they became trapped by the narrow exits, with people jumping from windows, in the worst industrial fire Bangladesh has seen. Fifty-two victims burned beyond recognition were buried in mass graves on Tuesday.

Around 1,000 workers took to the street to protest against “death trap” working conditions in most of the factories across the country.

About 700 garment workers have been killed in dozens of fire since 2006, according to Amsterdam-based textile rights group Clean Clothes Campaign.

Bangladesh’s garment industry, which employs three million people – mostly women – has driven the country’s poverty-stricken economy.