At least 273 Bangladeshi garment industry workers are dead following the collapse of Rana Plaza, an eight-storey factory near Dhaka making clothes for a host of Western brands, including Britain's Primark and the Spanish label Mango, which recently announced a deal to set up shops within David Jones in Australia.

Up to 3000 people were in the building when it collapsed on Wednesday morning, and rescuers have spent three days pulling survivors, and the bodies of those killed, from the rubble. It's still unknown how many people, alive or dead, remain trapped inside.

A group of 41 workers who survived the collapse were pulled from the wreckage to cheers from onlookers overnight on Thursday, but as each hour passes, the chances of rescuing more people alive diminishes.

On Friday those working on the site were still reporting that they were hearing people calling for help, but finding them, or getting them water and food, was becoming harder.

The demand for cheap clothes, and the resultant pressure on suppliers to cut costs, has undermined efforts to improve workers' conditions.

"What we're saying is that bargain-basement [clothing] is automatically leading towards these types of disasters," John Hilary, executive director at the British charity War on Want, told Reuters.

He said western clothing retailers' desire to undercut rivals put increasing pressure on foreign suppliers to reduce costs.

In the hyper-competitive garment industry, contracts are won and lost on fractions of a cent per item.

Building codes are ignored and protections for workers discarded in order to keep costs down, while thousands of workers are jammed onto tiny factory floors, some of which run around the clock, in order to increase productivity.

"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."

The president of the National Garment Workers' Federation of Bangladesh, Amirul Haque Amin, said Western companies were directly responsible for the deaths of workers.

"This negligence must stop. The deaths of these workers could have been avoided if multinational corporations, governments and factory owners took workers' protection seriously," he said.

"Instead, the victims' families must with live with the terrible consequences of this tragedy."

The garment industry in Bangladesh is second in volume only to China's. Some 5000 factories employ more than 3.2 million people. Most workers work 12-hour shifts, 30 days a month, for 3000 taka, about $37.

Mohammed Sohel Rana, the owner of the Rana Plaza, remains missing, after police filed charges against him and his father.

After large cracks appeared in the building on Tuesday afternoon, causing an evacuation, he appeared on local news saying the faults were "nothing serious".

Industrial police, however, had ordered him to shut the building until engineers could assess it.

They also discovered the top four floors of the building were constructed illegally, without any permits.

On Wednesday morning, the factories' workers gathered outside the building, but were reluctant to go in. Factory officials were sent out with megaphones, and some with sticks, to shepherd people inside, telling them their salaries would be docked if they didn't go back to work.

Mr Rana reportedly told staff as they were herded into the building that ?"it will stand for another 100 years".