- Second set of London, Beijing retests
- 23 were medalists from 2008 Olympics
- 98 athletes tested positive from 2008-12
- 15 tested positive from London Games
(CNN)Is there any chance that Rio will be a drug-free Olympics?
New analysis from the previous two Games has confirmed that 45 athletes tested positive for banned substances.
The International Olympic Committee made the announcement Friday after a second set of samples provided at the London and Beijing Olympics were reanalyzed.
According to information provided by the IOC, 23 of the 30 Provisional Adverse Analytical Findings (PAAFs) from Beijing were medalists, based on "A" samples across four different sports and eight different countries.
The London 2012 retests were even more conclusive, with 15 athletes' secondary "B" samples showing positive for drugs. These Adverse Analytical Findings (AAFs) involved 138 selected samples from two different sports and nine different countries.
The latest figures means 98 athletes have tested positive from 2008 through to 2012.
"The new reanalysis once again shows the commitment of the IOC in the fight against doping," IOC president Thomas Bach said in a statement.
According to the IOC, 1,243 doping samples from Beijing 2008 and London 2012 were selected to be reanalyzed in wave one and wave two.
The athletes, national Olympic committees and international federations concerned are in the process of being informed, with proceedings likely to follow.
The IOC said all athletes found to have infringed the anti-doping rules will be banned from competing at Rio 2016.
It said the third and fourth waves of tests will continue throughout and after the Olympics, which run from August 5-21.
Russia facing Rio ban
The announcement came just over 24 hours after the Court for the Arbitration of Sport rejected an appeal made by the Russian Olympic Committee and 67 athletes against being banned from the Rio Games.
Russia was suspended from track and field events by the International Association of Athletics Federations -- known as the IAAF -- back in November 2015.
"It's time to disband the IAAF," Russia's Sports Minister Vitaly Mutko said on Twitter Thursday, adding, '"Corrupt judges! How can you deprive clean sportsmen of their dream, and what's more WADA didn't present either facts or evidence."
Yelena Isinbayeva, Russia's two-time Olympic pole vault champion, also called on the IOC to have the final say after labeling the verdict as "purely political."
"Thank you everyone for the funeral of athletics," she said.
The IAAF suspension last year came after an independent World Anti-Doping Agency (WADA) report which uncovered a culture of state-sponsored doping.
Bach and the IOC's executive board will meet Sunday to discuss the CAS ruling and decide what sanctions to impose on the remainder of the Russian Olympic association and its athletes.
On Friday, President Vladimir Putin announced that the Russian Olympic Committee could launch an independent anti-doping commission.
"Sports must always be clean, and the health of athletes must be safeguarded," he said.
"To reach this goal we must closely cooperate with the International Olympic Committee, the World Anti-Doping Agency and all international sports federations," Putin was quoted as saying by the state-run Tass news agency.