Russia's 2014 World Cup squad is being investigated by FIFA as part of a widespread investigation into allegations of doping, FIFA has confirmed.
As many as 34 Russian footballers have been listed as "people of interest" in reports into 30 sports commissioned by the World Anti-Doping Agency (WADA) on Russia’s state-sponsored program of doping.
The 23 members of Russia’s squad for Brazil in 2014 are among those named, according the The Mail on Sunday.
"FIFA is still investigating the allegations made against [Russian] football players," said a FIFA spokesperson.
Four of the 2014 squad – goalkeeper Igor Akinfeev, plus outfield players Denis Glushakov, Maksim Kanunnikov and Aleksandr Samedov – were in the Russian team that was knocked out of the Confederations Cup on Saturday following a loss to Mexico.
The fifth player in the current squad is former Chelsea star Yuri Zhirkov.
Several players may have had their urine samples swapped for clean ones whether or not they were involved in doping, according to the story.
Former WADA chief Dick Pound, interviewed by the Mail in the report, said: "There is a huge onus on FIFA to reach a sensible conclusion on these matters before the World Cup takes place.
"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. Even within a governing body with as little credibility remaining as FIFA, if you were a senior official you wouldn't want to be part of a body that ignores this.
"There has been an institutional denial of doping in football for years … I've seen too many presentations by FIFA, straight out of fantasy land, about how they don't have a problem. They absolutely have to take this case seriously."
President of the Russian Football Union Vitaly Mutko has consistently denied there is any doping in Russian football.