Soccer World Cup 2018 in Russia (File)
The former head of Russia's national anti-doping laboratory Grigory Rodchenkov said urine samples from defender Ruslan Kambolov revealing banned anti-inflammatory dexamethasone were "definitely swapped" for clean ones in June 2015, public broadcaster ARD reported Monday.
The former lab chief said he had noted in his diary - also seen by ARD journalists - that an agent of Russia's FSB security service visited the lab on June 10 with a team of "magicians" to carry out the switch.
"Kambolov had been judged to be a doping case. FIFA knows this," Rodchenkov said.
Asked about the Kambolov case, a spokesman for the world football organisation told AFP it "cannot comment on potential anti-doping matters in relation to specific individuals".
FIFA in May ended a doping investigation into Russian footballers named in the country's provisional World Cup squad due to "insufficient evidence" of wrongdoing.
Kambolov was later dropped from the squad, although Russia said his removal was due to a calf injury suffered while playing with Rubin Kazan.
Whistleblower Rodchenkov has in the past provided key evidence leading to suspensions of Russian athletes from global sport, and now lives in hiding in the United States.
He predicted in May the 2018 World Cup should be "clean" as the higher financial stakes in football meant players and their coaches and agents were more wary of doping than Olympic athletes.
It was also ARD that broadcasted documentaries by journalist Hajo Seppelt which exposed doping among Russian athletes and ended up with Russia being banned from the 2018 Winter Olympics.