Traffic is severely backed up at the Beit Bridge border between South Africa and Zimbabwe, the Limpopo transport department said on Friday.

"We have received reports that traffic is heavy on the bridge to and from Zimbabwe," said spokesperson Boiki Tsedu.

Tsedu said there was also traffic towards Moria in Limpopo, where the Zion Christian Church celebrates Easter annually, but it was "flowing".

Earlier, a taxi accident on the N3 highway just before the De Hoek toll plaza near Heidelberg, Gauteng, left three people dead.

Netcare 911's Mark Stokoe said they received an emergency call saying a taxi had rolled several times and that it still had people trapped inside.

"Responding emergency workers found that three people had been killed in the accident, six were injured and were transported to hospital by ambulance," he said.

Stokoe said two people, an eight-year-old boy and 65-year-old man, were airlifted to hospital in a Netcare 911 helicopter.

Police spokesperson Constable Serathi Makgauta said the taxi was carrying passengers from Daveyton to Newcastle when it overturned.