The main assembly chamber was "completely gutted" by the initial blaze, which is thought to have broken out in an old parliament office building before spreading to the National Assembly on Sunday.

More than 70 fire crews were scrambled to tackle the fire, which saw black smoke billowing over the city, but the operation had been scaled back to 20 by Monday morning.

Firefighters were still working on "hotspots" of the blaze when further flames erupted, sparking concerns the entire structure could collapse.

Moloto Mothapo, head of communications for the parliament, tweeted on Monday afternoon: "Unfortunately after almost two days of brave battle with the flames in the National Assembly Building, more fire has just been fanned up.

"Firefighters remain at the scene and are continuing with the fight to bring the fire under control."

A 49-year-old man who was rescued from the fire on Sunday has been arrested and will appear in court on Tuesday.

He is expected to face charges of arson, theft, breaking and entering, and offences under South Africa's National Key Points Act, which controls access to places of national importance.

The parliament was not sitting as a result of the Christmas-New Year break and no one was reported injured.

It is not yet clear how the fire started again, but Patricia de Lille, minister of public works and infrastructure, said on Sunday that someone had turned off a valve which prevented a fire sprinkler system from functioning.

There have also been reports there was a lack of CCTV to monitor the incident.