The Department of Labour says its investigation into a building collapse in George will check whether economic migrants were permitted to work in South Africa.
Nine people have now been declared dead after another worker succumbed to his injuries in hospital.
A rescue mission is still ongoing to retrieve 44 people under the rubble.
Eighty-one workers were on site when the residential block of flats under construction crashed on Monday.
Labour Minister Thulas Nxesi said they approached the Mozambican, Malawian, and Zimbabwean foreign missions to assist.
“Let’s allow these investigations because sometimes, depending on the evidence we get, they can implicate people. We have to be meticulous in our processes,” he said.
“We have raised concern of how some employers have preferred foreign nationals because they are cheap labour.”
Meanwhile, Minister of Health Joe Phaahla will visit the injured victims in hospitals on Friday.
Phaahla will conduct a site visit to monitor the progress made by authorities to provide emergency medical and forensic services following the disaster.
Department of Health spokesperson Foster Mohale said the visit is part of ongoing efforts by the national government to support provincial and local government.
“Minister Phaahla will be accompanied by the MEC for Health in the province, Dr Nomafrench Mbombo, and senior health officials when he visits the disaster site in Victoria Street and the victims in George Hospital.”