South Africa has made an official complaint that athletes are switching the size of their running blades after Paralympic star Oscar Pistorius claimed longer prosthetics gave a rival an unfair advantage.
The International Paralympic Committee (IPC) received a letter on Tuesday morning alleging that athletes had changed the length of their blades, breaking competition rules.
Staff spoke to coaches in the athletes' village on Tuesday but found no evidence to back the South African claims.
Pistorius sparked controversy with angry comments he made after losing out on gold in the 200 metres. He alleged that Alan Fonteles Cardoso Oliveira's use of longer blades gave him an unfair advantage.
Craig Spence from the IPC said: "When we put that allegation to the coaches there was a look of shock to be honest because running on different size prostheses or swapping them for races is extremely difficult to do for an athlete.
"There is no evidence that any athlete competed on different size running blades. Unless the South Africans can come to us with some evidence that proves otherwise, it's something that we won't continue investigating."
He said that blades were measured before the heats and the final, and that running on different size prostheses would involving adapting to a different running technique.
The letter from the chief executive of the South African national Paralympic committee asked the IPC to "urgently" investigate its allegation. It also asked to meet with members of the committee to discuss the existing rules.
As things stand, it is against the rules to swap blades mid-competition, Mr Spence said.
Organisers contacted competitors in April asking them to raise any concerns about Paralympic regulations, and they heard nothing from South Africa, he added.