The International Olympic Committee is stepping up its drug-testing program ahead of the Olympics in Rio de Janeiro to focus on athletes from Russia, Kenya and Mexico.

The IOC executive board adopted a resolution Wednesday promising to take "further decisive action" in the fight against doping.

Its budget for pre-games testing ahead of the Rio Games will be doubled and there will be a "special focus" on countries whose anti-doping program is non-compliant with global rules, naming Russia, Kenya and Mexico.

In addition, the IOC will widen its re-testing program of stored samples from the 2008 and 2012 Olympics, saying it will target medalists from both games for possible re-analysis.

Fifty-five positive tests have already been recorded in re-testing of samples from the Beijing and London Games.

The announcement comes one week after Russia's Olympic Committee said eight of the country's athletes registered positive in doping re-tests for the 2012 London Games.

The brief statement from the IOC did not give names or what disciplines the athletes were in, but said they came from three different sports.

It said further information would not be released until so-called "B samples" were tested that would confirm or contradict the re-tests. The International Olympic Committee stores Olympic doping samples for 10 years to re-analyze them when newer methods become available.

Meanwhile, the IOC said last Friday said that 23 athletes from five sports and six countries had positive findings in re-tests with improved techniques on 265 samples from the London Games. The IOC did not identify the athletes, their sports or their nationalities. The current retesting program targeted athletes who could be eligible to compete in Rio.

The World Anti-Doping Agency announced this month that it has appointed an independent overseer for an investigation into allegations of state-sponsored doping in the Russian team at the 2014 Sochi Olympics.

In an interview published in The New York Times, Grigory Rodchenkov, the former head of the Russian lab now living in Los Angeles, said that he switched tainted urine samples for clean ones at the doping lab used for the Sochi Games, with help from people he believed to be officers of the Russian security services.

The Associated Press contributed to this report.