South African triathlete Mhlengi Gwala, who was attacked by three men who tried to cut off his legs with a blunt chainsaw, says he wants to compete again.

In an interview with the BBC's Focus on Africa program, Gwala described how the gang attacked him at gunpoint on Tuesday morning while he was riding to a training session in Durban.

"Then they start the chainsaw," he said.

"One man was holding my back, and another was holding my legs. And the other one cuts in [with the chainsaw]."

Gwala said he tried to call the police and a friend but they did not pick up.

"So I crawled to the road and then I stopped a car, and that car took me to hospital," he said.

The 27-year-old has undergone surgery since the attack.

The gang cut into Gwala's right calf, damaging muscle, nerves and bone, Dennis Jackson, the director of the elite athlete program for KwaZulu-Natal province, said.

The gash missed a main artery and surgeons hope they can save the leg, but are yet to see the level of nerve damage.

Doctors are confident they can save South African triathlete Mhlengi Gwala's legs. ( Facebook: Ironman South Africa )

Gwala became an athlete after overcoming drug and alcohol addictions, representing South Africa at international competitions in Chicago in 2015 and in the Netherlands last year, Mr Jackson said.

His long-term goals were to compete in half and whole ironman triathlons, which include swimming, cycling and running.

Gwala said he did not know why he was attacked, but that he hoped he would be able to compete again.

"People all over the world are praying for me … I'll carry on," he told the BBC.

The gang did not steal his money, phone and bicycle, and police are yet to make any arrests in the ongoing investigation.

A crowdfunding campaign has raised more than $69,000 for Gwala's medical expenses, transportation and rehabilitation costs.

ABC/wires