A spokesman for the International Olympic Committee declined to comment on the communications published Wednesday. Mr. McLaren did not immediately respond to a request for his reaction to the leaked emails.
Last month, the organization banned the Russian Federation from the 2018 Winter Games but left the door open for individual Russian athletes to compete as neutrals. While it has not yet been determined just how many Russian athletes will clear the bar for competition, some critics who advocated a blanket ban on Russian athletes have cautioned that the punishment could have too many loopholes and enable Russia to send a sizable delegation.
Much of the information published Wednesday was unsurprising, reflecting routine logistical discussions among investigators, lawyers and Olympic staff members regarding, for example, the retesting of urine samples from the 2012 London Games and the 2014 Sochi Games, where Russia cheated most elaborately.
Fancy Bear emphasized, however, that some of the investigators who had worked to expose the details of Russia’s cheating also had done work for the United States and British governments. As examples, the hackers pointed to Martin Dubbey, who worked with Mr. McLaren, and David Tinsley, the chief executive of 5 Stones intelligence and a former agent for the Drug Enforcement Administration. Neither man immediately responded to a request for comment on Wednesday.
Some antidoping officials said that while the hackers might have intended to embarrass or expose them, the information only underscored their efforts to disentangle the jobs of sports officials — who are tasked with promoting competitions and making them profitable — from the work of drug-testing officials working to root out cheating that damages the brand image of those competitions.
“If anything it shows what we’ve said since Day 1 of our existence: You can’t both promote and police,” Travis T. Tygart, the chief executive of the United States Anti-Doping Agency, said Wednesday. “You have to have independent organizations handling antidoping operations.”
Fancy Bear first published the private medical records of Western athletes — a majority of them American and British — in the summer of 2016, at the peak of the Russian doping scandal. Those medical records, reflecting that certain athletes had received special medical permission to use banned medications, sought to discredit the athletes in question, none of whom had committed a violation, sports officials said.
Last year, American intelligence officials published a declassified report linking Fancy Bear to Russia’s main military intelligence unit, the G.R.U., and attributing to the group hacks of both the World Anti-Doping Agency and the Democratic National Committee.
“The genuine intentions of the coalition headed by the Anglo-Saxons are much less noble than a war against doping,” the Russian hackers wrote on their website, echoing Russian officials’ repeated claims of Western conspiracies seeking to undermine Russia and calling Mr. McLaren’s investigation of Russian sports cheating “a smoke screen for special agents.”
“It is apparent that the Americans and the Canadians are eager to remove the Europeans from the leadership in the Olympic movement,” they wrote, “to achieve political dominance of the English-speaking nations.”