SAVAR, Bangladesh (AFP) - Rescue workers were searching for survivors late into the night Wednesday after a building containing five garment factories collapsed in Bangladesh, killing at least 113 people.

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 9am (0300 GMT).

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. "Many people are still trapped".

Fire fighters and soldiers cut through the building's collapsed sixth floor and managed to rescue 20 people eight hours after the accident, he said.

"We will continue searching for survivors through the night, for as long as it takes," he said.

Deputy chief of Dhaka police A.B.M Masud Hossain said that at least 113 people have died in the disaster. "But the toll will be higher because some relatives took bodies without informing police," he said.

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.