South African police said Wednesday that they had arrested a man accused of starting a fire that killed more than 70 in Johannesburg last year.

The 29-year-old was detained on Tuesday after confessing his involvement before an enquiry established to investigate the tragedy.

"A suspect was arrested in connection to the Marshalltown fire," police spokeswoman Dimakatso Nevhuhulwi said.

Seventy-seven people were killed and scores injured as a blaze ripped through a five-storey building taken over for illegal housing in central Johannesburg last August.

It was one of the deadliest building fires worldwide in recent years.

The suspect is expected to appear in court "soon" on charges of arson, 76 counts of murder and 120 counts of attempted murder, police said.

Illegal occupation of disused buildings in the city centre is widespread, with many said to be under the control of criminal syndicates who collect rent from occupants.