The organisation’s Mechanical Aids Review Panel said the 31-year-old American, who won two Paralympic medals at London 2012, could not compete using the RSPs in competitions against able-bodied athletes.

In its verdict the panel said: "World Athletics has satisfied its burden of proof on the balance of probabilities that the use of the mechanical aids by Blake Leeper in the form of passive-elastic carbon-fibre running specific prostheses (RSPs) that give him a leg length of 104 centimetres and a standing height of 184 centimetres provides Blake Leeper with an overall competitive advantage over an athlete not using such aids, with the result that the use by Blake Leeper of such RPSs in any World Athletics sanctioned events is not allowed pursuant to Rule 6.3.4 of the Technical Rules of World Athletics."

The ruling followed an application submitted by Leeper in December 2020 to run on RSPs in the same competitions as able-bodied athletes, including in World Athletics sanctioned 400 metre races and the Tokyo 2020 Olympic Games, if he was selected.

Following the application, an extensive testing process was completed by Leeper at Southern Methodist University in Texas over a two month period in February and March.

In its judgement, the five member World Athletics panel, formed in January 2021, ruled that Leeper was "running unnaturally tall" using the RSPs.

Under the Maximum Allowable Standing Height (MASH) rule, Leeper is not permitted to run at a height greater than 174.4 centimetres.

In the tests conducted at Southern Methodist University, Leeper’s standing height with the RSPs was measured at 184 centimetres with a leg length of 104 centimetres.

This made the difference between the height allowed in the MASH rule and Leeper’s standing height 9.6 centimetres, and the panel ruled "the only conclusion that is open is that Mr Leeper is running unnaturally tall in using his new RSPs."

The panel concluded there was a direct link between leg length and running speed and said that "the height of Mr Leeper’s RSPs result in him running faster in the 400m event than would otherwise be the case."

World Athletics ruled in February 2020 that Leeper would not be able to compete against able-bodied athletes at events sanctioned by the organisation using prosthetics.

Leeper appealed this decision to the Court of Arbitration for Sport (CAS) which upheld the ban on the prosthetics being used against able-bodied athletes.

Leeper has appealed this decision to the Swiss Supreme Court and in the aftermath of the CAS ruling described the MASH rule as "racially discriminatory."

In this judgement, the World Athletics panel concluded "that the weight of rational scientific opinion is to the effect that the MASH rule does have application to black athletes of African descent," adding that it was "confident that there is a scientifically proved basis upon which the MASH rule has the asserted application."

Following today’s World Athletics ruling, Leeper confirmed he would appeal the latest judgement to the CAS.

"It's not right that World Athletics continues to discriminate against disabled black athletes, and that the panel they appointed has again sanctioned this discriminatory treatment," said Leeper.

"Basing this decision on standards and studies that completely excluded black athletes goes against common sense and has no scientific basis, as my experts' submissions to World Athletics made clear.

"But despite this setback, I will appeal so I can continue to fight for athletes around the world who are discriminated against - whether on the basis of race, disability, or both - and look forward to making my case before the Court of Arbitration for Sport as I pursue my longtime dream of competing at the 2021 Tokyo Olympic Games."