World-Anti-Doping Agency (WADA) investigator Richard McLaren has told German TV network ARD that 155 samples related to Russian footballers have been reported to FIFA, saying he believed those samples were part of a doping cover-up.
McLaren said he believed this could be part of a cover-up separate to that revealed in the report that led to the banning of Russian athletes from the Olympic Games in Brazil.
"There are 155 samples that were seized by WADA and are awaiting analysis. We have reported those to FIFA," McLaren said.
He added that he believed the samples had either been opened and manipulated or would show the existence of doping substances.
"Either there's been tampering with the caps so that contents could have been changed, or the contents haven't been changed but there may be prohibited substances in there," he said.
"That gives rise to a suspicion that there is a bank of clean samples and that it's been used with respect to footballers."
Citing the example of one test in June 2015, McLaren said there was evidence that a positive sample from a Russian Premier League footballer, sample No. 387829, could have been swapped.
ARD reported that it had "learned that sample 387829 was not just anyone's. It was taken from one of the current national football players."
It added: "The world football federation [FIFA] should appoint a special investigator. McLaren thinks there is sufficient evidence."
FIFA, UEFA, the Russian Football Union and the Russian Ministry of Sport have yet to respond, ARD said.
Reacting to the report, Germany coach Joachim Low told a news conference: "If it's true, I'd like to read all the names in the paper once and also hear them in public.
"I would like to see FIFA or WADA or whoever conducts those tests just call a spade a spade, and then we'll see what happens.
"Those institutions, which permanently test us at training sessions, in training camps and after matches, I would like to hear names from them. If players have used doping, they have to be suspended."
The news comes days after the Mail on Sunday reported that FIFA "are investigating whether Russia's entire 23-man 2014 World Cup squad were part of a state-supported doping programme and cover-ups."
World football's governing body has confirmed that an investigation is ongoing.
The Mail on Sunday report was rejected by Russian Deputy Prime Minister Vitaly Mutko, who told the TASS news agency it was "nonsense."
Russia is hosting the 2018 World Cup and is currently staging the 2017 Confederations Cup which has reached its final stages.
Information from ESPN FC's Germany correspondent Stephan Uersfeld was used in this report.