LONDON  Track and field’s world governing body ruled on Monday that Oscar Pistorius, a double-amputee sprinter from South Africa, is not be eligible to compete in Olympic qualifying events. The International Association of Athletics Federations explained in a statement that, after an independent scientific study, it deemed Pistorius’s state-of-the-art carbon fiber prosthetics “should be considered as technical aids which give him an advantage over other athletes not using them.”

Pistorius’s agent, Peet Van Zyl, said that he and Pistorius were seeking legal advice in order to prepare an appeal. “We need to speak with the I.A.A.F. first and see what approaches we can follow there,” Van Zyl said in a telephone interview from South Africa. “The last resort will probably be the Court of Arbitration for Sport.”

Pistorius, 21, was born without fibulas and had both legs amputated below the knee when he was 11 months old. But in the four years since he started competing, he has set Paralympic world records in the 100, 200 and 400 meters and it was his dream to compete in the Olympic Games.

The I.A.A.F. had originally cleared him to compete against able-bodied athletes last June, pending further scientific examination of his j-shaped blades, known as Cheetahs. But in the meantime, Pistorius became the focus of an intense ethical debate over the limits which should be placed on technology. So last November, the I.A.A.F. arranged for Pistorius to travel to Cologne, Germany, where he was tested for two days under the supervision of Peter Brueggemann, a professor at the German Sport University.