FIFA has condemned Fancy Bears for publishing a list of players who were allegedly permitted to use prohibited substances for medical reasons at the 2010 World Cup.
The hacker group on Tuesday leaked a document which claimed that Argentina's Carlos Tevez, Diego Milito, Juan Sebastian Veron and Gabriel Heinze were among 25 footballers who were granted Therapeutic Use Exemptions (TUEs) during the tournament in South Africa.
Netherlands forward Dirk Kuyt and Germany striker Mario Gomez were also named on the list, which detailed substances that certain players were granted permission to use due to health concerns.
There is no suggestion in the leaked document that any of the players named had breached anti-doping regulations.
In response, football's world governing body was critical of the hacker group.
"FIFA condemns in the strongest terms the publication by the Fancy Bears group of information obtained illegally, particularly personal and medical data from athletes," a FIFA statement read.
"The release of such information constitutes a clear violation of the athletes privacy and puts at risk the ongoing fight against doping.
"All potential violations of the anti-doping regulations are handled by FIFA in accordance with WADA regulations. We have no further comment at this stage."
The list was published as part of a release that included claims that 160 unnamed footballers failed doping tests in 2015.
Fancy Bears revealed what it said was a document from the World Anti-Doping Agency (WADA), detailing examinations carried out across world football.
In a statement posted via their website accompanying the documents, Fancy Bears said: "Greetings citizens of the world.
"You can have a look at WADA documents revealing that more than 150 players were caught doping in 2015. The next year this number increased up to 200 athletes."
Like FIFA, WADA has subsequently responded to the leak, denying that the medical records had been obtained from a hack into their system.
"The World Anti-Doping Agency (WADA) is aware that, today, cyber espionage group 'Fancy Bear' once again released information; in particular, confidential athlete data regarding Therapeutic Use Exemptions (TUEs) on its website," a statement read.
"As WADA takes data privacy very seriously, the Agency immediately examined the information; and, was quickly able to determine that it is not housed in WADA's Anti-Doping Administration & Management System (ADAMS).
"Stakeholders can rest assured that ADAMS remains secure. We take this opportunity to reiterate that the TUE process is a means by which an athlete can obtain approval to use a prescribed prohibited substance or method for the treatment of a legitimate medical condition.
"The TUE program is a rigorous and necessary part of elite sport, which has overwhelming acceptance from athletes, physicians and all anti-doping stakeholders worldwide.
"This criminal activity undertaken by the cyber espionage group, which seeks to undermine the TUE program and the work of WADA and its partners in the protection of clean sport, is a clear violation of athletes' rights."
|Barcelona 6 Eibar 1: Majestic Messi leads romp with four goals for LaLiga leaders|
|Burnley 2 Leeds United 2 (aet, 3-5 pens): Lonergan the penalty hero as Championship leaders cause cu|
|I´m the first to trust young players - Conte defends Chelsea youth record|
|Matic and Fellaini have never been this good – Mourinho tells Carrick, Herrera to be patient|
|Tottenham 1 Barnsley 0: Alli sees off stubborn Tykes|
|Bologna 1 Inter 1: Contentious Icardi spot-kick maintains Spalletti´s unbeaten run|
|Leicester City 2 Liverpool 0: Okazaki, Slimani dump Klopp´s men out of EFL Cup|
|Schalke 0 Bayern Munich 3: James scores on first Bundesliga start|
|Atletico benefiting from competition of fringe players - Simeone|
|Manchester City have got two players for every position - Delph|
|Bayern could say they don´t need me – Lewandowski accepts football´s cut-throat nature|
|Montella to keep on rotating as he plans for long season|
|Billionaire investor announces he is ´done´ funding Hamburg|
|Wenger confirms Welbeck groin injury|
|Ljungberg sad to leave Wolfsburg|
|Ferdinand, McGregor and Curry - Sport´s most notable crossover stars|
|Messi has his story, I have mine - Dybala plays down compatriot comparisons|
|Hazard to start against Nottingham Forest as Conte prepares to rotate|
|New Real Madrid contract ´already done´ for Zidane|
|Chelsea won´t appeal David Luiz red card, Conte confirms|
|Mbappe and Dembele lead Golden Boy nominees|
|Dembele tipped for early January return after successful surgery|
|I hope it´s the last time – Zidane relieved to welcome back Ronaldo|
|Szczesny to face Fiorentina as Allegri calls for Juventus consistency|
|Gundogan fears he might never return to top form after Manchester City injury nightmare|
|Kick It Out contact Manchester United over ´offensive´ Lukaku chant|
|Bayern Munich goalkeeper Neuer ruled out until January|
|Cologne drop protest against Borussia Dormtund VAR goal|
|Ferdinand wants to recapture ´chemical of competition´ from boxing|
|Barcelona not planning January signings despite Dembele injury|
|Neville trolls Ferdinand as Manchester United great starts boxing career|
|Manchester United great Rio Ferdinand to launch boxing career|
|Oxlade-Chamberlain relieved to join Liverpool from Arsenal, says Klopp|
|Case closed! Tianjin Quanjian dismiss Aubameyang links|
|Tevez has not met expectations, says Shanghai Shenhua chairman|
|Socceroos pair Jedinak and Rukavytsya return to squad for World Cup play-off|
|Allegri not the reason for Bonucci´s Juve exit – wife|
|Hazard: I improved after a week with Conte at Chelsea|
|We aren´t far off Real Madrid – Herrera sees no reason for De Gea to head home|
|Manchester City obliged to win title after spending so much - Herrera|
|Barcelona president Bartomeu criticises Neymar over lack of honesty|
|Feyenoord fans banned from Champions League trip to Napoli|
|PSG star Mbappe must prove he has Madrid quality, says Morientes|
|Impossible to stop Icardi, says Spalletti|
|Sevilla president urges fans not to ´insult´ returning Vitolo|
|Goals will come soon for struggling Suarez, insists Barca boss Valverde|
|It´s the hardest thing for a player – Valverde sympathises with crocked Dembele|
|Neuer out of Schalke trip with foot injury amid reports of long lay-off|
|West Ham have new plan to manage Carroll, says Bilic|
|Carvajal: My release clause is to stop me leaving Real Madrid!|
|Lazio star Milinkovic-Savic has suitors ´in Madrid, Manchester and Milan´|
|Ancelotti focused on Bundesliga business before PSG showdown|
|Klopp backs Liverpool forwards despite Burnley failings|
|Rooney reception leaves Mata proud of Manchester United fans|
|Klopp: Cups bring opportunity, not pressure, for Liverpool|
|Martin Schmidt takes charge at Wolfsburg|
|Pochettino targets Tottenham improvement|
|Giving De Boer time would have been ´negligent´, Palace chairman claims|
|Sacchi suggests Ancelotti should leave Bayern Munich|
|Cologne claims are ´ridiculous and grotesque´, says Dortmund´s Zorc|
|Cahill frustrated Chelsea could not break Arsenal down|
|Fulham experience means Hodgson will not panic at Palace|
|Dembele flies to Finland for surgery|
|Misfiring champions Anderlecht sack coach Weiler|
|Conte backs Christensen to replace David Luiz for key Chelsea triple-header|
|Rooney apologises for ´unforgiveable lack of judgement´|
|Wayne Rooney given two-year driving ban, 12-month community order for drink-driving|
|Wolfsburg sack Jonker after Stuttgart defeat|
|Players fear Dybala, says Juventus great Del Piero|
|Llorente insists trophies are within Tottenham´s reach|
|Don´t blame Tevez – Shanghai Shenhua´s Cao Yunding calls for unity|
|Rooney due in court on drink-driving charge|
|Real Madrid whistles ´normal´, says Bale|
|Navas lauds ´excellent´ Bale after goal in Madrid win|
|Wenger happy with Lacazette display|
|Emery tells Cavani and Neymar to sort it out after penalty disagreement|
|WATCH: Stephen Curry scores penalty at Stamford Bridge|
|He demonstrated the player he is – Zidane salutes Bale´s goalscoring performance|
|CAF Champions League Review: Sundowns snare first-leg advantage over Casablanca|
|Koeman takes swipe at Mourinho after ´top four´ claim|
|Dortmund CEO brands Cologne bad losers for demanding to replay a 5-0 defeat|