Bangladeshi police say they have arrested two owners of garment factories based at the eight-storey building that collapsed outside the capital this week, killing hundreds of people.
The death toll in the disaster rose to 324 after rescuers removed more bodies - most in a state of decay - from the wreckage.
Dhaka police deputy chief Shyaml Mukherjee says some workers have been pulled out alive as the desperate hunt for survivors continued through the night.
Police have filed a case against two owners for "death due to negligence", he said, after the prime minister said the owners forced the workers to return to work despite cracks having appeared in the building a day earlier.
"We've arrested Bazlus Samad, the chairman of New Wave Buttons and New Wave Style factories, and Mahmudur Rahaman Tapash, a managing director of one of these plants, after midnight," Mr Mukherjee said.
Survivors said the building developed visible cracks on Tuesday evening, but factory bosses had demanded staff return to the production lines despite a police evacuation order.
One manager for the New Wave Styles company, one of the five manufacturers in the building, said the owner had consulted an engineer but then ignored his warnings.
Earlier yesterday, police battled to control huge crowds of angry garment workers protesting over the tragedy, the latest to befall Bangladesh's huge garment sector, which is a big foreign exchange earner for the poor nation.
Widespread anger has been fuelled by revelations that factory bosses forced workers to return to the building on Wednesday.
Police fired tear gas and rubber bullets at the workers who sew clothes for well-known Western brands for as little as $US37 a month after they blocked roads and attacked factories and buses in textile-making districts around Dhaka.
