A leading official says amputee runner Oscar Pistorius should not be allowed to compete in the 4x400m relay at the Olympics because of safety concerns.
"It's a decision that rests with the officials of the federation and the South African Olympic Committee," said IAAF general secretary Pierre Weiss.
"But we would prefer that they don't select him for reasons of safety."
Pistorius needs to run a personal best in Lucerne on Wednesday to have any chance of making it to the Olympics.
The 21-year-old South African, whose best time is 46.36 seconds, clocked a time of 46.62 in Rome last week, well short of the Olympic qualifying standard of 45.55.
A good performance on Wednesday could see him in contention for a place on South Africa's 4x400m relay squad.
But Weiss, an IAAF official for 23 years, said Pistorius risked the physical safety of himself and other athletes if he ran in the main pack of the relay, where only the first leg is run in lanes.
606: DEBATE
"The relay is a scrum," said IAAF spokesman Nick Davies.
"It is one of the few events where there is physical contact between athletes. You are jostling, crouched down at the line waiting for the baton in a group lined up hip to hip."
He added that Pistorius could cause "serious damage" if he ran in the relay.
"When you get the baton you fly straight to the inner curve, so there is a massive potential for disaster on changeovers," he said.
However, Pistorius's manager Peet van Zyl said that the plan was for the 21-year-old to run the first leg of any relay.
Pistorius was cleared to run against able-bodied athletes in May after the Court of Arbitration for Sport (Cas) overturned a ruling from the IAAF that his prosthetic racing blades give him a competitive advantage.
But Davies said the IAAF still had concerns over the CAS ruling, which cleared Pistorius to compete only if he used the same model of Cheetah blade that was subjected to laboratory testing.
"There is still a big issue over the prosthetics," said Davies. "We just don't have the resources to check every time he is running what he is using.
"If Oscar runs 44.7 in Lucerne, we would be totally stupid not to do something because you shouldn't improve by two seconds in two weeks."
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