Labour Minister Membathisi Mdladlana alleged that the employer at the construction site where a partially built office collapsed in Little Falls, Roodepoort on Thursday had been aware of cracks in the construction.

The Star newspaper reported on Friday that Mdladlana said the workers had complained about cracks in the walls but that their employer insisted they continue working on the site.

"We heard building inspectors were here but they are not from the Department of Labour. They alleged it was safe while workers saw cracks in it (the structure)," he told the newspaper.

A construction worker who had been on site when the building fell, Joseph Nevhuhlulu, said there had been cracks in the building over the past few weeks and alleged that the owner was aware of the cracks.

The building started shaking on Wednesday and inspectors were called to the site but workers were instructed to continue working after the site was found to be safe.

The Department of Labour had issued the construction company responsible for the site, Dunehill Investments, with a notice of prohibition to stop work on the site until the department had finished their investigations.

Efforts to speak to the employer failed because he referred them to his lawyers, Mdladlana told the newspaper, and information had to be gleaned from an injured worker.

Honeydew police Inspector Karen Jacobs said attempts to rescue a trapped worker had stopped around 10pm on Thursday because the area where sniffer dogs had reacted and rescuers were working had started to collapse.

Rescue work resumed at 6am on Friday.

The worker, identified by the Star newspaper as 23-year-old Artur Magaizane, was still believed missing under the rubble.

She added that the top part of the rubble had become extremely unstable.

Engineers were being called in to advise on how to proceed. They would decide on the correct way to proceed with the rescue effort.

At present rescue workers were excavating the rubble from the side using heavy earth moving equipment.

Sapa