By Mark Trevelyan

VIENNA (Reuters) - Paralympic long jump champion Markus Rehm saw his dream of competing at the Rio Olympics fade on Friday after the IAAF said that the German had failed to prove that he does not gain an unfair advantage as a prosthesis-wearing athlete.

Nicknamed "Blade Jumper", the 2012 Paralympics gold medalist and 2014 German national long jump champion was hoping to become the second athlete with a carbon fiber prosthesis to compete at the Olympics after South Africa's Oscar Pistorius in 2012.

However, IAAF president Sebastian Coe, speaking at a news conference where Russia's ban from the sport was extended, said: "He has to prove that the prosthetic he uses does not give him a competitive advantage and at this stage he has not been able to do that."

Rehm had commissioned a scientific study, hoping to prove he did not get an advantage, with a report last month indicating no clear edge over able-bodied athletes.

A new IAAF ruling requires amputee competitors to prove themselves they do not have an advantage over able-bodied athletes.

The study was conducted by several universities in Germany, the United States and Japan and showed that amputee such as Rehm, who lost his lower right leg in a boating accident as a teenager, had a less efficient start but a more efficient jump.

The 27-year-old jumped a para-athletics world record of 8.40 meters to win the 2015 IPC world title in Doha, a distance that would have beaten Britain's 2012 London Olympics gold medalist Greg Rutherford by nine centimeters.

(Additional reporting by Mitch Phillips and Karolos Grohmann; Editing by Toby Davis)