South African firefighters have gone back inside the Johannesburg building destroyed by fire on Thursday to see if they can find any more bodies.

The blaze, in the overcrowded and condemned five-storey building, claimed 74 lives, including 12 children.

The fire service says it wants to be sure that no-one has been left behind.

The cause of the fire is still unknown but forensic investigators are also at the site, picking through the charred remains of the burnt-out building.

A canine search team has also gone into the wreckage, which is less smoky and has cooled down since Thursday.

Looking on at the operation are some survivors, who bear the scars of their ordeal in the form of broken bones and head injuries.

Relatives who believe that family members may have been among the victims of the fire have been asked to visit the mortuary to help identify the bodies.

But officials say that out of the 74 corpses, 62 have been burned beyond recognition and they hope to use DNA samples to help in the identification process.

The government has promised help to all the victims but it is a very difficult situation for many of them as they are undocumented migrants. Some fear that coming forward could expose them to the authorities.

Tanzania's Acting High Commissioner Peter Shija has said that he has so far found out that five of his compatriots died in the blaze and three were injured. He told South African news broadcaster eNCA that 150 Tanzanians had been living in the building before it was engulfed in flames.

Visiting the scene in central Johannesburg on Thursday evening, President Cyril Ramaphosa called the tragedy a "wake-up call for us to begin to address the situation of housing in the inner city".

The building used to be a home for abused women and children, but once the lease expired, it was "hijacked", President Ramaphosa explained to reporters.