Companies such as Primark and the UK government need to do more to improve conditions for workers in Bangladesh, a British charity says.
Graciela Romero, of War On Want, says firms who use Bangladeshi products must "safeguard the life of these workers".
A factory complex collapsed on Wednesday on the outskirts of the capital Dhaka, killing some 350 people.
Primark said it "accepts all its responsibilities in this disaster" and was providing assistance in the region.
A protest was held outside Primark's flagship store in London on Saturday following the disaster.
Ms Romero, War On Want's Director of International Programmes, said businesses that employ people in Bangladesh "have the power to change the situation there and to basically safeguard the life of these workers and it's not happening".
"They need to act now, and the UK government needs to basically establish regulation to control these brands and then to protect the lives of workers in Bangladesh."
Primark occupied a floor of the collapsed building and workers there were suppliers to the brand.
A spokesman for the company said: "Primark shares 98% of its factories with other well-known retailers. Through the Ethical Trading Initiative, the company will continue to work to improve working conditions, as it has been for several years.
"The company accepts all its responsibilities in this disaster. It is providing assistance in the region, and will take further steps in due course."
A petition has now been launched by War On Want, calling for Primark and other retail brands which used the building's products to compensate the families of workers killed or injured.
Campaigners also want Primark, with Matalan and Mango, which have also used the building's products, to sign the Bangladesh Fire and Building Safety Agreement of firms, unions and non-governmental organisations aimed at ending the "appallingly unsafe factory conditions" in that country.