LAUSANNE, Switzerland — The IOC is standing behind the anti-doping rule that will prevent American runner LaShawn Merritt from defending his 400-meter gold medal at the 2012 London Olympics.

The IOC executive board and athletes’ commission declared their full backing Wednesday for the rule, which bars any athlete with a doping suspension of at least six months from competing in the following games.

The Olympic officials rejected claims that the rule amounted to a second punishment, saying it is the IOC’s right to rule on who can participate in its event.

“The athletes made it very clear they support the rule,” International Olympic Committee vice president Thomas Bach said. “The rule applies. It shows the full resolve of the IOC in the fight against doping and demonstrates that Olympic athletes serve as role models worldwide.”

The rule was approved by the IOC in 2007 and went into effect just before the 2008 Beijing Olympics.

Merritt, winner of the 400 meters in Beijing and the world champion in 2009, received a 21-month suspension last year after testing positive for a banned substance found in a male enhancement product.

His ban expires in July, meaning he can return to international competition, including possibly the world championships in Daegu, South Korea. But Merritt is ineligible to compete in London a year later because of the IOC rule.

“We made it clear from the very beginning that it is not a sanction,” said Bach, a German lawyer who heads the IOC’s juridical commission. “It is a condition of participation. The IOC is governing the Olympic Games and has the right to put conditions for participation.”

The American arbitrators who banned Merritt have contested the IOC rule, saying it goes against the World Anti-Doping Agency code and would essentially extend his ban to three years.

Bach acknowledged the rule could face legal challenges, possibly in the Court of Arbitration for Sport.

“We will see what happens,” he said. “We are interested to solve it as soon as possible.”

Merritt was given 21 months instead of the usual two-year suspension because he cooperated with authorities and was found to not have taken the drug to enhance athletic performance.

U.S. Anti-Doping Agency CEO Travis Tygart said Wednesday the IOC rule might be counterproductive by discouraging athletes from offering to cut deals to help catch cheats.

In a statement to The Associated Press, Tygart said each case should be reviewed by an independent legal panel “to determine the fairness of the automatic application of the IOC rule.”

“The review process should be fundamental given that the rule goes beyond the WADA Code and unintentionally has had the effect of both deterring those who would otherwise provide substantial assistance to anti-doping authorities and causing tribunals to reduce the standard WADA Code sanction clearly to circumvent the IOC rule,” Tygart said.

Frank Fredericks, a former Namibian sprinter who chairs the IOC athletes’ commission, said he personally favored even tougher measures — lifetime Olympic bans for dopers. The British Olympic Association has such a policy.

“I like the rule,” Fredericks said. “If we could all adopt it, it would solve a lot of things. We would know that anyone who tests positive would not compete in the Olympics. If the rest of the world could adopt that, it would be nice. It would give more credibility to any Olympic champion.”

But Fredericks said lifetime bans were less acceptable to the majority of his commission.

“When you try to weigh the two, it seems like the (IOC) rule is a nicer one to have than the BOA rule,” he said.

Among others who could be affected by the rule is American basketball star Diana Taurasi, who tested positive for the stimulant modafinil in November while playing in the Turkish women’s league. Taurasi, who helped the U.S. win gold medals at the past two Olympics, could be banned for up to two years.

Also facing a possible London ban is American swimmer Jessica Hardy, who missed the Beijing Olympics after testing positive for clenbuterol. She was found to have unknowingly taken the banned agent in a contaminated food supplement and her two-year suspension was reduced to one.