Friday 27 May 2016 17:46, UK
The International Olympic Committee has confirmed that 23 competitors from the 2012 London Olympics have failed doping retests.
The IOC said 265 London samples had been retested with improved techniques, and the 23 failures come from competitors from six countries, competing across five sports.
The athletes have not been named but Sky Sports News HQ understands that no British athletes are involved.
It is understood there has been no contact between the IOC and the BOA over the matter, and that no British athlete has returned a positive sample.
The London athletes are in addition to the 31 caught in retests of samples from the 2008 Beijing Olympics. The Russian Olympic Committee has confirmed that 14 of those athletes were Russians.
The IOC still has to retest the athletes' 'B' samples. Formal positive cases are not declared until the 'B' samples confirm the original findings.
The IOC said the retests targeted athletes who were hoping to compete at the Olympics in Rio de Janeiro in August.
IOC president Thomas Bach said: "These reanalyses show, once again, our determination in the fight against doping.
"We want to keep the dopers away from the Olympic Games in Rio de Janeiro. This is why we are acting swiftly now.
"I have already appointed a disciplinary commission, which has the full power to take all the decisions on behalf of the IOC."
It was also revealed that one more sample from Beijing had shown "abnormal parameters" and would also be followed up on.
The samples were re-examined after intelligence-gathering that began last August, the IOC said in a statement.
It has been working with the World Anti-Doping Agency (WADA) during that period.
UK Anti-Doping (UKAD), meanwhile, welcomed the reanalysis of samples from both the Beijing and London Olympics.
"The ability to retest samples, as a result of new intelligence or the development of new testing techniques, is a vital tool in the fight against doping in sport," said UKAD's director of operations Pat Myhill.
"Retrospective analysis allows us to pursue those who cheat clean athletes, long after the competition has ended.
"It sends a clear message to those who dope - if you chose to make that choice, and think that you've got away with it, think again. We can, and will, catch you."
