A South African woman has been discovered alive in a morgue shortly after being declared dead in a car crash.

The woman was found breathing by mortuary technicians several hours after being certified dead by paramedics at the scene of the pile-up outside Carletonville, southwest of Johannesburg.

"We followed our procedures - we've got no idea how it happened," Distress Alert operations manager Gerrit Bradnick told AFP.

"The crew is absolutely devastated - we're not in the business of declaring living people dead, we're in the business of keeping people alive."

The unnamed woman from Gauteng had "showed no signs of life" following the traffic accident in the early hours of 24 June, Bradnick added.

She was found alive in a morgue fridge several hours after the crash in which the victims' car rolled, throwing all three occupants out of the vehicle - killing two of them.

After being discovered alive, the woman was taken to Carletonville hospital where she is now recovering.