South Africa's transport minister has described how she was robbed at gun-point after her vehicle stopped on a highway to change a burst tyre.

Sindisiwe Chikunga told a parliamentary committee that one of the masked attackers pointed a gun at her head during the ordeal early on Monday.

They stole some laptops, a phone and her bodyguards' weapons, she said.

South Africa has long faced high crime levels, including car-hijackings, kidnappings and smash-and-grabs.

But it is very unusual for a government minister travelling with armed bodyguards to be robbed in their vehicle.

"I'm in one piece, but the whole experience was very traumatising," Ms Chikunga told MPs.

She said that at 03:30 local time on Monday her bodyguards - or "protectors" - had got out of the car, which had been travelling on a main road south of Johannesburg, to replace a burst tyre.

That was when the robbers approached, forcing the bodyguards onto the floor and then opening the car door.

They "pointed a gun at my head and ordered me to come out", Ms Chikunga said.

They demanded money, but she explained that she did not have any cash on her. They then searched through the vehicle taking what they could find.

Still threatening her with their guns, the robbers also tried to take the minister's ring but she told them: "This was the only thing that I have between my late husband and myself, I value it so much."

At one point the minister started praying but was told to keep quiet.

"We are fine, we are healthy, we are alive. It was a horrible experience... but God had mercy on us," Ms Chikunga told parliamentarians as she wrapped up her account of what happened.

The police have confirmed that the robbery took place and "a manhunt has since been launched following this unprecedented incident", the AFP news agency reports quoting police spokesperson Brig Athlenda Mathe.

Referring to a common method that criminals use, the ministry of transport said that the tyres of the car "were punctured by spikes [placed on the road], bringing the car to a stop enabling the criminals to rob the occupants of valuables".

The two bodyguards have been placed on leave "until [they are] fit and proper to return to their posts", Brig Mathe is quoted by News24 as saying.

"Steps are under way to determine what transpired as far as VIP protection protocols are concerned," she added.

In the latest annual survey nearly 1.3 million people said they had been victims of property crime, which amounts to almost 3% of the population.

The proliferation of small arms is also a big issue in South Africa. Guns were used in more than 66,000 of the recorded home robberies.