NEW YORK (AFP) - The former head of Russia's anti-doping laboratory has alleged that dozens of Russian athletes including at least 15 medalists at the 2014 Winter Olympics were part of an extensive state-run doping programme, the New York Times reported on Thursday.

Grigory Rodchenkov, fearing for his safety and now living at a secret location in Los Angeles, told the Times he developed a three-drug mix of banned performance-enhancing substances combined with alcohol and given to dozens of athletes in one of the most elaborate doping plots in sports history.

Up to 100 tainted urine samples were replaced with clean ones collected months before, Rodchenkov said, with samples passed through a hole in a lab wall at night, aided by only a single dim lamp.

The report alleged that Russian officials involved in the plot had found a way to access supposedly tamper-proof containers used to collect urine samples without anyone knowing.

"We were fully equipped, knowledgeable, experienced and perfectly prepared for Sochi like never before, Rodchenkov said. "It was working like a Swiss watch."

The revelation comes as pressure mounts for Russian athletes to be banned from taking part in the Rio de Janeiro Olympics in August and amid calls for greater investigations into sport in Russia, where the 2018 Fifa World Cup is set to be staged.

Russia was suspended from international athletics events last November, although in the next few weeks officials will consider lifting the ban ahead of Rio.

Wada said independent observers watched over the lab randomly during the day but rarely during overnight hours, never seeing the hole thanks to a small cabinet blocking it from view when not being used.

Rodchenkov resigned after a Wada report last November and moved to Los Angeles.

In February, after his departure, two former close anti-doping colleagues in Russia died unexpectedly, one after resigning soon after Rodchenkov left Russia.

Russians won the most medals of any nation at the Sochi Winter Games with 33 including 13 golds. No Russian athletes were reported as failing doping tests.

By contrast, the Russians were sixth in the medal count at the 2010 Vancouver Winter Olympics.

"People are celebrating Olympic champion winners but we are sitting crazy and replacing their urine," Rodchenkov said.

Rodchenkov outlined the details to the newspaper in interviews over three days arranged by Bryan Fogel, a US filmmaker working on a documentary about the scandal.

Rodchenkov also gave the newspaper e-mails detailing the doping plot plus a spreadsheet naming athletes involved that he said was provided by the Russian sports ministry before the 2014 Olympics.

One-third of all medals went to athletes named on the spreadsheet, including double gold bobsledder Alexander Zubkov, cross country ski champion Alexander Legkov and men's skeleton winner Alexander Tretyakov.

Vitaly Mutko, Russia's sports minister, was quoted by the Times as saying that the revelations were "a continuation of the information attack on Russian sport." Mutko's deputy, Yuri Nagornykh, met with Rodchenkov at least once a week in the six months before the Sochi Winter Olympics, Rodchenkov said.

Nagornykh denied any doping program existed in an e-mail to the Times, saying, "I have nothing to hide."

Billions of dollars were spent for Sochi to be a showcase for Russian sport success, with Russian President Vladimir Putin involved in much of the planning for the event.

Rodchenkov was identified last November by the World Anti-Doping Agency (Wada) as part of a state-sponsored Russian doping programme, accusing him of extorting money from athletes, a claim Rodchenkov denied.

Wada also said he covered up positive drug tests and destroyed hundreds of urine samples in the report, which focused upon athletics.

Rodchenkov said he destroyed thousands of urine samples to protect the secret doping plot.

Rodchenkov said the drug cocktail helped Russian athletes recover quickly following tough training sessions, Chivas whiskey for men and Martini vermouth for women used to shrink the detection window and help absorption of the steroids, with a precise formula of one milligram of the steroid mix for each milliliter of alcohol.

But not every doping story was a success, Rodchenkov said, citing a Russian women's hockey team that was entirely comprised of dope cheats yet finished sixth.