(CNN) The Kremlin has dismissed allegations of doping at the Sochi 2014 Olympics Games as "defamation by a defector."
The Putin administration is responding to a report in the New York Times, in which the former head of the country's anti-doping laboratory claimed at least 15 Russian medal winners at the event were part of a state-sponsored doping program.
Grigory Rodchenkov told the paper he developed a three-drug cocktail that was given to dozens of athletes, but those claims drew short shrift from a Kremlin spokesman.
"I would say that these statements seem completely proofless and aren't based on any sort of information deserving trust and are not backed by any sort of argumentation," presidential spokesman Dmitry Peskov told state-run news agency Sputnik.
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The NYT said it was unable to independently verify Rodchenkov's account. CNN was not able to verify details of the NYT report.
However, the Russian Sports Ministry admitted it must "regain the international community's trust" in a statement released in the aftermath of Rodchenkov's allegations.
Earlier this year, Russia's track and field athletes were banned from the upcoming Rio Olympics after the World Anti-Doping Agency (WADA) found that doping was endemic within Russian sport.
"We have never claimed that we do not have doping problems and we acknowledge that changes are needed," the sports ministry said in a statement responding to Rodchenkov's allegations.
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"We believe we have already proved Russia's commitment to fight doping by inviting international experts recommended by WADA to all key positions responsible for doping controls and this guarantees independence and transparency of procedures.
"We have nothing to hide. And we will continue this work."
Rodchenkov resigned shortly after WADA removed Russia's right to test samples in the wake of an independent report by its former head Dick Pound.
It confirmed he had quit in a statement released in the aftermath of the report being published but the Russian Sports Ministry claimed that Rodchenkov had in fact been fired.
"The allegations made by the former director of the laboratories came as a major shock to us considering that he was fired from his position for manipulating tests -- it is very likely that he has other motives," it said.
"This simply looks like, you know, defamation by a defector or something like that I wouldn't trust these types of unfounded statements," Peskov added.
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A recent CBS "60 minutes" report claimed Rodchenkov shared incriminating information with Vitaly Stepanov, a former employee in Russia's anti-doping agency who turned whistle-blower to WADA.
The program reported Rodchenkov as saying that a minimum of four Russian athletes had won gold medals in Sochi while on steroids, and that his lab had covered it up.
He went on to allege that agents working for the FSB, Russia's federal security service, had effectively worked as doping control officers in a bid to manage the entire process.
The New York Times said Rodchenkov was now in California with documentary filmmaker Bryan Fogel.
WADA president Craig Reedie said the organization would investigate Rodchenkov's claims.
"You can be sure that WADA will immediately look into these additional allegations," Reedie said in a statement.
Meanwhile the International Olympic Committee said the fresh allegations were "very worrying" and called on WADA to "investigate immediately."
"A WADA independent observer team monitored all anti-doping activities during the Sochi Olympic Winter Games and produced a satisfactory report following the Games," it added.
"Based on the findings of a WADA inquiry the IOC will not hesitate to act with its usual policy of zero tolerance for doping and defending the clean athletes."