Leaked WADA documents printed in The New York Times state that there is not enough evidence to pursue a case against all but one of a 96-strong group.
WADA has been investigating individual athletes implicated in the doping scandal which has embroiled Russia.
None of the 96 athletes – the first to be reviewed by WADA – have been named.
“The available evidence was insufficient to support the assertion of an anti-doping rule violation against these 95 athletes,” said WADA director general Olivier Niggli in a report seen by The New York Times.
The newspaper has also reported that WADA officials did not receive testimony from Grigory Rodchenkov, the former head of the Moscow Laboratory who turned whistleblower.
His allegations led to investigations into Russian doping as well as two editions of the highly-critical McLaren Report.
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