Bangladeshi authorities say 275 bodies have been recovered from the rubble of a building that collapsed in the country's worst ever disaster for its notoriously unsafe garment industry.

Brig.-Gen. Mohammed Siddiqul Alam Shikder, who is overseeing rescue operations, said Friday morning that 61 survivors have been rescued since Thursday afternoon.

Authorities say more than 2,000 people have been rescued from the building since it collapsed Wednesday.

Deep cracks visible in the walls of a Bangladesh garment building had compelled police to order it evacuated a day before it collapsed, officials said Thursday, but factories based there ignored the order and kept more than 2,000 people working.

Wednesday's disaster in the Dhaka suburb of Savar is the worst ever for Bangladesh's booming and powerful garment industry, surpassing a fire less than five months earlier that killed 112 people. Workers at both sites made clothes for major brands around the world; some of the companies in the building that fell say their customers include retail giants such as Wal-Mart.

Joe Fresh, a Canadian company owned by Loblaw Companies Ltd., issued a statement on Wednesday confirming that "a small number" of Joe Fresh-branded products were manufactured at the complex.

"We will be working with our vendor to understand how we may be able to assist them during this time," said the statement, which was attributed to vice-president of public relations Julija Hunter.

Hunter said that Loblaws Inc. has "robust vendor standards to ensure that products are manufactured in a socially responsible way, ensuring a safe and sustainable work environment."

Hunter that while their company's audits align with industry around the world, the measures do not address the issue of building construction or integrity.

"We want to improve and we want to find a solution that helps stop these incidents from happening," Hunter said, adding that Loblaws is in the process of reaching out to other industry groups to review and address Bangladesh's approach to factory standards.

Meanwhile, hundreds of rescuers, some crawling through the maze of rubble in search of survivors and corpses, worked through the night and into Thursday amid the cries of the trapped and the wails of workers' relatives gathered outside the building, called Rana Plaza. It housed numerous garment factories and a handful of other companies.

An Associated Press cameraman who went into the rubble with rescue workers spoke briefly to a garment worker pinned face down in the darkness between concrete slabs and next to two corpses. Mohammad Altab pleaded for help, but they were unable to free him.

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"Save us, brother. I beg you, brother. I want to live," Altab moaned. "It's so painful here.… I have two little children."

Another survivor, whose voice could be heard from deep in the rubble, wept as he called for help.

"We want to live, brother. It's hard to remain alive here. It would have been better to die than enduring such pain to live on. We want to live. Please save us," the man cried.

Rescue efforts going slowly

After the cracks were reported in the walls of Rana Plaza on Tuesday, managers of a local bank that also had an office in the building ordered their employees to leave. The garment factories, though, kept working, ignoring the instructions of the local industrial police, said Mostafizur Rahman, a director of that paramilitary police force.

The Bangladesh Garment Manufacturers and Exporters Association had also asked the factories to suspend work starting Wednesday morning, hours before the collapse.

"After we got the crack reports, we asked them to suspend work until further examination, but they did not pay heed," said Atiqul Islam, the group's president.

Marchers protest poor safety standards

Thousands of workers from the hundreds of other garment factories in the Savar industrial zone took to the streets to protest the factory collapse and poor safety standards for the country's garment workers.

Television reports said that hundreds of protesting workers also clashed with police in Dhaka and the nearby industrial zone of Ashulia. It was not immediately clear whether there were any injuries in those clashes.

Rescue workers combed through the debris of the collapsed garment factory on Thursday searching for survivors. (Andrew Biraj/Reuters)

The garment manufacturers' group said the factories in Rana Plaza employed 3,122 workers, but it was not clear how many were in the building when it collapsed.

Searchers worked through the night to probe the jumbled mass of concrete with drills or their bare hands, passing water and flashlights to people pinned inside.

"I gave them whistles, water, torchlights. I heard them cry," said fire official Abul Khayer late Wednesday, as he prepared to work late into the night.

Abdur Rahim, an employee who worked on the fifth floor, said he and his co-workers had gone inside Wednesday morning despite the cracks in the building, after a factory manager gave assurances that it was safe. About an hour later, the building collapsed. The next thing Rahim remembered was regaining consciousness outside.

"Our thoughts and prayers go out to the injured and those who lost family members or friends in this tragedy," Foreign Affairs Minister John Baird said in a statement.

Canada "remains concerned about dangerous working conditions in the global ready-made-garment sector," he said. "We stress the importance for all governments to take concrete measures to provide workers with safe and healthy working conditions."

Police looking for factory owners

Abdul Halim, an official with the engineering department in Savar, said the owner was originally allowed to construct a five-storey building but added another three storeys illegally.

Firefighters try to rescue garment workers trapped inside the rubble of the collapsed Rana Plaza building, in Savar, 30 kilometres outside Dhaka. (Andrew Biraj/Reuters)

On a visit to the site, Home Minister Muhiuddin Khan Alamgir told reporters the building had violated construction codes and that "the culprits would be punished."

Local police Chief Mohammed Asaduzzaman said police and the government's Capital Development Authority have filed separate cases of negligence against the building owner.

Habibur Rahman, police superintendent of the Dhaka district, identified the building owner as Mohammed Sohel Rana, a local leader of the ruling Awami League's youth front. Rahman said police were also looking for the owners of the garment factories.