Johannesburg  - South Africa's amputee sprinter Oscar Pistorius underwent emergency surgery in a Johannesburg hospital Sunday following a boating accident, the Sapa news agency reported.

"We are not sure what happened at this stage, we are still trying to establish it," Pistorius's manager Peet van Zyl said.

Meanwhile local radio reported that Pistorius, who is nicknamed "Blade Runner" because of the prosthetic legs that enable him to sprint, was in a serious but stable condition and had been placed on a ventilator in an intensive care unit in Milpark Hospital.

"He was involved in a boating accident on the Vaal River on Saturday night, but the extent of the injuries and details of the accident will only be known after he comes out," said Van Zyl.

Pistorius, who had both legs removed between the knee and ankle as a baby, missed out on qualification for last summer's Beijing Olympics after the Court of Arbitration for Sport (CAS) lifted a ban on him competing against able-bodied athletes.

He went on to win three gold medals at the Paralympics. dpa