The IAAF has refuted fresh doping allegations after it was claimed athletics’ world governing body turned a blind eye to suspicious blood tests involving 150 athletes, including a leading Briton.

German TV broadcaster ARD reported that a 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.

The alleged cases involved blood samples taken between 2006 and 2008 and were “highly suspicious” according to the unnamed medical commission member, but there was no follow-up involving target testing of the athletes involved by the IAAF’s doping department.

But the chairman of the IAAF medical and anti-doping commission Dr Juan Manuel Alonso said on Twitter that “blood samples taken before 2009 were thoroughly examined’’.

The IAAF stressed in an official statement 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”.

It is claimed by ARD that many of the samples in question came from Russians, but that three Britons were also involved along with others from Kenya, Germany, Spain and Morocco.