A total of 23 competitors from the 2012 London Olympics failed retrospective drug tests as part of a large retest by the International Olympic Committee.<br />The IOC retested 454 doping samples from the 2008 games in Beijing and 265 from the 2012 London games, BBC reports.<br />Athletes from five different sports and six different countries are among the positive tests from London.<br />Last week the committee said that 31 athletes in six sports tested positive from Beijing.
