Rescue workers were searching for survivors late into Wednesday night after a building containing five garment factories collapsed inBangladesh, killing 124 people and injuring over 1,000.

Only the ground floor of the eight-storey Rana Plaza in Savar town just outside the capital Dhaka remained intact when the block - which one minister said was illegally constructed - imploded at about 9:00 am.

Armed with concrete cutters and cranes, hundreds of fire service and army rescue workers struggled in the hope of finding more survivors in the mountain of concrete and mangled steel, which resembled the aftermath of an earthquake. Corpses and the injured were pulled from the higher reaches of the pile of flattened floors via makeshift slides made from cloth that just hours earlier was being cut into shirts and trousers for export to Western markets.

"The whole building collapsed like a pancake within minutes. Most workers did not have any chance to escape," national fire department chief Ahmed Ali said. "We can still hear the faint cries of some trapped people."

Fire fighters and soldiers cut through the building's collapsed floors and managed to rescue around hundreds of people, he said, adding "the search for survivors will continue through the night, for as long as it takes".

Hospitals in and around Savar were overwhelmed with patients with serious head and chest injuries and some without limbs, Hiralal Roy, an emergency doctor of Enam Medical College, said, adding the clinic treated more than 1,000 people.

The cries of people inside the rubble begging for rescue could be heard as thousands of relatives waited anxiously nearby, some chanting the name of Allah. "Save us please!" a woman worker cried from inside. "We're 30 people here. Please save us."

Survivors complained that the building had developed cracks on Tuesday evening, triggering an evacuation, but they had been ordered back to the production lines.

Mustafizur Rahman, head of a police unit created to handle industrial troubles, said the factory owners, who have gone into hiding, ignored a warning not to open their plants.

Factories in the building were making clothing for some top European retailers including Mango of Spain, according to campaign groupBangladeshCenterfor Workers Solidarity. Mango spokeswoman Marta Soler Morera told AFP by email that it did not have any suppliers at the building, "although we did have contacts with one of them to produce a test production, as we do with several suppliers".