Oscar Pistorius has been ruled ineligible to compete at this summer's Olympic Games because his prosthetic limbs give him an unfair advantage.

The International Association of Athletics Federations (IAAF) announced their decision this morning after studying the findings of a two-day independent scientific investigation last November.

Their statement said the double amputee's "cheetah" blades were technical aids in clear contravention of IAAF rules, effectively banning the South African, 21, from competing against able-bodied athletes.

Pistorius has already said he would take legal action in his bid to run in Beijing if the decision went against him .

The IAAF statement today said: "It is evident that an athlete using the 'cheetah' prosthetic is able to run at the same speed as able-bodied athletes with lower energy consumption.

"Running with prosthetic blades leads to less vertical motion combined with less mechanical work for lifting the body. As well as this, the energy loss in the blade is significantly lower than in the human ankle joints in sprinting at maximum speed.

"An athlete using this prosthetic blade has a demonstrable mechanical advantage (more than 30 per cent) when compared to someone not using the blade."

Pistorius' only course of action now appears to be an appeal to the Court of Arbitration for Sport.

The IAAF announcement confirmed the opinion expressed last month by Professor Peter Bruggemann, who conducted the research at the German Sport University in Cologne. Pistorius underwent tests over two days with five able-bodied athletes who were capable of similar levels of performance at 400 metres.