South African Olympian and Paralympian Oscar Pistorius has enlisted US investigators to assist the legal team that is defending him against charges of murdering his girlfriend Reeva Steenkamp.

Mr Pistorius is due to stand trial in the North Gauteng High Court in March next year for shooting the model at his Pretoria home on 14 February.

The athlete, who has been free on 1 million rand (€74,000) bail, has said he mistook Ms Steenkamp for an intruder.

"I can confirm that a team of forensic specialists from the United States is in the country at the moment working with Oscar's defence team," spokeswoman Anneliese Burgess said.

"We don't want to go into any further details except that it's very standard practice to work with specialists in various fields in preparation for any trial."

Ms Steenkamp, 29, locked herself in a toilet cubicle, and Mr Pistorius, armed with a 9mm pistol, fired four shots at her through the locked door, according to his indictment.

The cause of death was given as multiple gunshot wounds.

Known as Blade Runner for the prosthetics he wears to race, Mr Pistorius won six Paralympic gold medals and in 2012 became the first amputee runner to compete in an Olympic Games.

He was born without fibulas and had both legs amputated below the knee at 11 months old.

Sponsors, including Nike and Oakley, have ended deals with Mr Pistorius since his arrest.