Organisers of the London Marathon have criticised athletics' governing body, the International Association of Athletics Federations, for its "failure to take effective action" in the war on doping.
Nick Bitel, chief executive of the London race, said he was "disappointed" in the IAAF after fresh allegations made by the British newspaper, the Sunday Times, in the continuing doping storm which has thrown the sport into turmoil.
Thirty-two medal winners at the world's six top city marathons were among the hundreds of long distance runners with suspicious blood test results revealed in a leak, the newspaper reported.
It said the London Marathon was won seven times over a 12-year period by athletes who had given suspicious blood tests at some point in their careers.
No athletes were named in the claims but London organisers said they had never been informed of abnormal blood test results at their event "between 2001 and 2012, or subsequently."
The claims prompted Bitel to release a statement saying the Marathon would "be discussing the implications of the allegations with the IAAF."
On BBC radio's Sportsweek programme, Bitel added that, although the Marathon paid "tens of thousands of pounds" to test athletes, it did not administer the procedures and did not see the results, so were unaware of any abnormal tests.
"We are disappointed," he said. "We're doing more than anybody else to fight doping in our sport.
"What this story is really about is the IAAF's failure to take effective action. Those athletes that have been caught have only been caught because of the tests at the London Marathon.
"The IAAF needs to do more to stop people from starting (races) that have blood values that are out of normal range."
Last week, the Sunday Times and German broadcasters ARD said data, leaked by a whistlebower, showed that between 2001 and 2012 a third of Olympic and world championship endurance and middle distance running medals had been won by athletes who, at some point, had given a suspicious blood test.
The IAAF stripped Russian Liliya Shobukhova of her medals since 2009 last week, including three victories in the Chicago marathon and one in London.
The IAAF has defended its drugs testing procedures strongly and refutes suggestions of turning a blind eye to doping, says it is cooperating with the independent World Anti-Doping Agency (WADA) in an investigation into the allegations.