Chairman of the IAAF medical and anti-doping commission Dr Juan Manuel Alonso took to Twitter yesterday to refute the allegation that the world governing body ignored 150 suspicious blood tests.

German TV broadcaster ARD reported that a long-time member of the IAAF’s medical commission, whose identity has not been revealed, had a list of dozens of questionable blood values which were not followed up.

But Alonso defended the IAAF by saying that “blood samples taken before 2009 were thoroughly examined.”

An official IAAF statement said that a member of that commission would not know whether follow-up tests had been conducted or not and said it was not possible to conclude whether an athlete had doped “on the basis of one single blood value.”