Federation Internationale de Football Association would not confirm a report in the Mail on Sunday that all 23 squad members were among those being investigated by the sporting body, but did reveal that it is looking into allegations that footballers were among the Russian athletes who were involved in or benefited from "institutionalised" doping between 2011 and 2015.
Russia, hosts of next summer's 2018 World Cup, are also now hosting the Confederations Cup with five members of that 2014 team - Igor Akinfeev, Denis Glushakov, Maksim Kanunnikov, Aleksandr Samedov and Yuri Zhirkov - all part of the squad that was eliminated from the competition by Mexico on Saturday.
And FIFA insisted all players, including all of the Russian squad, underwent pre-competition and post-match tests in Brazil. Five of the 23 players tested in 2014 are members of the squad that was knocked out of the Confederations Cup on Saturday. "The same procedure is now being applied for the FIFA Confederations Cup 2017".
A Fifa spokesman told the Mail On Sunday: "Fifa is still investigating the allegations made against the football players".
The Mail cited a source who said some players may have had their urine samples swapped out for clean batches regardless of whether they were involved in a doping programme. "However, FIFA did not refer to any particular players, since it can not comment on the status of ongoing investigations", the spokesperson told R-Sport.
The McLaren report, commissioned by the World Anti-Doping Agency (WADA) and published a year ago, found that more than 1,000 athletes competing in summer, winter and Paralympic sports were assisted by an "institutionalised manipulation of the doping control process in Russia".
"Our team is being tested all the time; we have doping control at every match".
The new allegations, coupled with concerns over hooliganism and the mistreatment of migrant workers working on the country's stadiums to stage World Cup matches, are likely to throw Russia's suitability to stage the 2018 finals into serious doubt.
Wada recommended all Russian competitors be banned from Rio 2016, but the International Olympic Committee (IOC) left it up to individual sports' governing bodies to decide.
Two reports commissioned by the World Anti-Doping Agency found at least 1,000 athletes were involved in a state-sponsored doping programme.
"It is incumbent on them to say what steps they are taking, what they find and take whatever action necessary to protect the integrity of sport".
"They absolutely have to take this case seriously".