Eight Russians were among the 23 athletes at the 2012 Olympics in London to have tested positive for retrospective doping tests, the Russian Olympic Committee has said. The athletes have not been named and will not be until the second round of testing has been completed which could take weeks.

But it was revealed they took part in different sporting events and will not be allowed to compete at the Olympic Games in Rio.

"These re-analyses show, once again, our determination in the fight against doping," Thomas Bach, the IOC president, said in a statement on Friday. "We want to keep the dopers away from the Olympic Games in Rio de Janeiro."

The IOC retested as many as 454 selected doping samples from the 2008 Games in Beijing, in which high jumper Anna Chicherova, who won bronze in 2008, came out as being one of 14 Russian athletes that failed the retest last week. Chicherova vowed to clear her name, saying: "It's the most complete shock. I can't explain how it could have happened. I was always sure what supplements and medicines I was using."

The IOC is also currently testing 250 samples from London 2012. A World Anti-Doping Agency (WADA) report indicated there was "systematic" doping in Russia and the country was under investigation.

Russia doping
A technician holds a test tube with a blood sample at the Russian anti-doping laboratory in Moscow Sergei Karpukhin/Reuters