Two Russian athletes have admitted taking banned performance-enhancing substances given to them by Grigory Rodchenkov, the scientist who says he orchestrated a massive state-sponsored doping programme before the 2014 Sochi Winter Olympics.

The Russian authorities deny such a programme existed but Rodchenkov, who headed the country’s main anti-doping laboratory from 2005 to 2015, says at least 14 medal winners took part and that tainted urine samples from Russian athletes were substituted for clean ones to help them pass drug tests at the Games. This is the first time any Russian athletes have confessed to using doping cocktails supplied by Rodchenkov, who fled to the United States last year.

The anonymous athletes told Match TV, Russia’s biggest sports channel, that the substances were supplied to them by Rodchenkov in unmarked pill containers, dissolved in the mouth and washed down with alcohol.

“They weren’t to be used every day but whenever I felt I was tired, so as to speed up the recovery process,” one of the athletes told the Kremlin-funded TV channel. “The effect was very powerful.”

An athletics manager, also speaking anonymously, told the TV channel the substances were provided to “elite” athletes. A third athlete said she only pretended to take the banned substances and she was unaware of their exact contents.

The athletes interviewed did not allege, however, that Russian officials other than Rodchenkov were involved in doping. “Doping was a business for Rodchenkov and one he had been involved in for many years,” Sergey Lisin, the author of the Match TV report, told the Guardian. “My sources did not claim this was a government-run doping programme.” Lisin denied his report was an attempt to discredit Rodchenkov.

Russia’s investigative committee said this week that Rodchenkov destroyed the drug test samples of Russian athletes and that Russia intends to seek his extradition from the US. Investigators also said they had found no evidence of a Kremlin-backed doping system.

Two investigations commissioned by the World Anti-Doping Agency in 2015 and 2016 revealed widespread state-sponsored doping in Russia. The International Olympic Committee is due to decide next month on whether to allow Russian athletes to compete at the 2018 Winter Olympics in South Korea. Russia is currently barred from international athletics.

Russia’s president, Vladimir Putin, has admitted that the country was unsuccessful in its attempt to tackle the use of performance-enhancing steroids, but denied the existence of a state-sponsored doping programme. The Kremlin spokesman Dmitry Peskov called Rodchenkov’s allegations “slander by a turncoat”. Vitaly Mutko, the deputy prime minister, said the accusations were part of an international effort to discredit Russian sport.

Meanwhile, four more Russian cross-country skiers, including the Olympic silver medallist Maxim Vylegzhanin, were found guilty on Thursday of doping at the Sochi Olympics by the IOC. The Russian cross-country ski federation said the four have been disqualified by the IOC and banned from all future Olympics.

The other three skiers found guilty are Alexei Petukhov, Yulia Ivanova and Evgenia Shapovalova. Vylegzhanin won three silver medals in Sochi but none of the others were medallists.

Six Russian cross-country skiers have now been found guilty of doping at the Sochi Olympics by an IOC commission. Alexander Legkov, who won gold in the 50km race ahead of Vylegzhanin in a Russian sweep, and Evgeniy Belov were banned last week.