The International Olympic Committee has discovered seven more positive drugs results from re-testing samples taken at last year's Beijing Olympics.
The IOC says 948 samples were analysed and seven, from six athletes, tested positive for the new generation blood booster CERA.
The latest round of testing began in January and focused primarily on endurance events in cycling, rowing, swimming and athletics.
The IOC stores samples for eight years to allow re-testing once new methods of detecting banned substances are developed.
Nine athletes tested positive at Beijing after extensive pre-Games testing nabbed about 40 while six horses in the equestrian events were also found to have been given banned substances.
The IOC conducted the largest ever doping operation with about 5000 blood and urine tests during the Games.