The N1 South Highway between the Beyers Naude and Rivonia offramps were heavily congested on Saturday, due to road works, Johannesburg metro police said.

Spokesperson Superintendent Wayne Minnaar warned motorists to avoid using the highway as it was backed up for kilometres.

"It is due to construction. They blocked it off to only one lane," said Minnaar.

He advised motorists travelling to the south of Johannesburg to rather use the M1, while motorists travelling west should use the N14 and the N3 to go to the O.R. Tambo International airport.

"I expect the situation to be the same for the rest of the day," he said.