Monday 6 June 2016 15:24, UK
Kazakhstan says five of its athletes have failed retests from the 2008 and 2012 Olympic Games.
The athletes were not named and it was not immediately clear in which events they competed.
The Central Asian nation has faced repeated doping scandals in recent years, particularly in weightlifting and cycling.
The IOC is retesting samples from the Beijing and London Olympics to catch cheats who might be competing this year in Rio de Janeiro. So far, 55 positives have been recorded - 32 from Beijing and 23 from London.
Separately, the Russian Olympic Committee says two of its athletes' 'B'' samples came back negative.
They are race walker Denis Nizhegorodov and rower Alexander Kornilov.
Athletes must provide 90ml of urine or a blood sample. If there are 'adverse analytical findings' in the 'B' sample as well as the 'A' the athlete will be banned for violating anti-doping regulation.
'B' samples are not more important than 'A' samples, but they confirm findings in the first analysis. If the analysis of the 'B' sample does not confirm the findings in the 'A' sample, the athlete is cleared to compete.
WADA Director General David Howman said: "The 'B' sample helps confirm that an anti-doping rule violation has occurred and protects the rights of the athletes.
"It should be stressed that anti-doping is one of the few types of controls in society in which a confirmation procedure is used in order to protect individuals, and the very rare cases in which the analysis of the B-sample did not match the results of the A-sample have shown the usefulness of such procedure."
