At least 260 people, mainly female workers, were killed and more than 1,000 were injured when the eight-storey Rana Plaza factory building in Savar, 30 km (20 miles) outside the capital Dhaka, collapsed on Wednesday. "What we're saying is that bargain-basement (clothing) is automatically leading towards these types of disasters," John Hilary, executive director at British charity War on Want, told Reuters.
He said western clothing retailers' desire to undercut rivals has translated into increasing pressure on foreign suppliers to reduce costs.
"If you've got that, then it's absolutely clear that you're not going to be able to have the right kind of building regulations, health and safety, fire safety. Those things will become more and more impossible as the cost price goes down."
Hilary said the push for lower costs inevitably led to factories cutting corners. "As a result of that, we see the sort of disaster that happened yesterday," he said.
War on Want and its partner in Bangladesh, the National Garment Workers' Federation, called on major international buyers to be held to account.
"This negligence must stop. The deaths of these workers could have been avoided if multinational corporations, governments and factory owners took workers' protection seriously," NGWF president, Amirul Haque Amin, said in a statement.
Gareth Price-Jones, Bangladesh country director of British charity Oxfam, said western companies had not done enough.
"Western buyers could be doing much, much more, and they have a moral responsibility to do so," he told Reuters. "Western buyers really need to press for decent wages and safe working conditions."
He said Bangladeshi building regulations were not robust enough for construction in an earthquake zone and were, in any case, frequently ignored.
Around 4,500 Bangladeshi factories produce clothes for many of the world's major brands, employing 4 million workers and generating 80 percent of Bangladesh's $24 billion annual exports, making it the world's No. 2 apparel exporter behind China.
But with wages as low as $37 a month for some workers toiling for 10-15 hours a day, and increasing publicity about unsanitary and unsafe working conditions, some retailers were getting worried about their reputation.