A sign is seen on the outside of the Russian National Anti-doping Agency (RUSADA) in Moscow, Russia, May 24, 2016. AP

Doha, Qatar —The World Anti-Doping Agency is giving Russia three weeks to explain possible signs of tampering with data from its doping laboratory that was critical to prosecuting cases against athletes alleged to have cheated at the 2014 Olympics and other major events. WADA heard about the possible tampering at its executive committee meeting Monday in Tokyo.

Turning over the data was a key requirement for the reinstatement of Russia's anti-doping agency, and WADA has formally opened a compliance procedure that could lead to a new ban if the data was manipulated.

Russia's sports minister Pavel Kolobkov said his office had been told about the discrepancies between the data turned over by a whistleblower and data from the lab, which was being used to corroborate the whistleblower information. He indicated that Russian technical specialists will have access to the review.

"What, exactly, these inconsistencies are and what they are related to, that will be cleared up by experts in the field of digital technology from both sides, who are already cooperating," Kolobkov said. "From our side, we will continue to offer all possible assistance."

The data was handed over to WADA in January after Russia breached an earlier deadline of Dec. 31, 2018. It has already been used to bring cases against athletes in weightlifting and biathlon, and WADA said it would continue to pursue cases while this latest review is ongoing.

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WADA has been criticized for reinstating RUSADA under terms less stringent than the original roadmap. But director general Olivier Niggli told The Associated Press he stood by the decision.

"I believe it was actually a very important decision and absolutely the right decision," Niggli said. "I'm convinced that we would not have the data if we had not taken that decision, so we would not even be talking about it today. There would still be a cloud of suspicion and nothing would have gone forward."

WADA would not set a firm timetable on a decision. The case is heating up a few days before the start of the track world championships in Doha, where 30 Russians will compete as neutral athletes while Russia's track federation remains under suspension by the sport's governing body.