“It is not clear to us how the accident happened, but we are trying to find out the cause,” Mohammad Atiqul Islam, president of the Bangladesh Garment Manufacturers and Exporters Association (BGMEA), said.
Six were cleared to reopen on Thursday after inspectors issued safety certificates.
Collapse death toll reaches 912
Salvage teams were still pulling bodies from the rubble of the Rana Plaza complex in Savar, around 20 miles (30km) northwest of Dhaka, and on Thursday a spokesman at the army control room coordinating the operation said the number of people confirmed to have been killed had reached 912.
Roughly 2,500 people were rescued from the building, including many injured, but there is no official estimate of the numbers still missing.
The government has blamed the owners and builders of the eight-storey complex for using shoddy building materials, including sub-standard rods, bricks and cement, and not obtaining the necessary clearances.