In The 'Secret World of Doping', broadcast on Wednesday evening in Germany, ARD made a number of revelations pertaining to some of the country's top athletes and officials.

Among these was the suggestion that Mutko allowed infamous racewalking coach Viktor Chegin - who was handed a lifetime ban by the World Anti Doping Agency in 2015 - to carry on in his role

The report also suggested Mutko played a key role in covering up a doping case involving a player from Russian football team FK Krasnodar. The top-flight side played German club Borussia Dortmund in the group stages of the 2015 Europa League.

The allegations against Mutko are based on a confidential email exchange between the Ministry of Sport and a Doping Control Laboratory that was leaked to reporter Hajo Seppelt by a source within the ministry.

In the case of the footballer, who is currently unnamed, the show alleges that prohibited drug Hexarelin was detected in a drugs test in August 2014. The sample was marked "to be approved by VM" - thought to refer to Mutko.

The documentary claimed that the results of the sample were never published and the player in question never punished.

To muddy the waters even further, Mutko is on the council of football's governing body FIFA and is the chairman of the organizing committee of the 2018 World Cup in Russia.

The allegations, which came shortly after the unrelated doping suspension of Russian tennis player Maria Sharapova, cast a shadow over Russia's Euro 2016 opener against England on Saturday. But Mutko, who is also president of the Russian Football Union said that wouldn't stop him attending: "Of course I will travel to the European Championships," he said on Wednesday.

The Kremlin was quick to deny the allegations broadcast. Spokesman Dmitry Peskov told Interfax news agency: "This does not mean that we accept any unsubstantiated claims and unproven allegations."

The news comes just days before world athletics' governing body the International Association of Athletics Federations (IAAF) is set to rule on whether to reinstate the Russian athletics federation ahead of the August 5-21 Rio Olympics.

ARD also screened footage dated April 27 showing that the former chief trainer for the speed walking team, Viktor Chegin, was still involved in the training of national athletes, even though he had been banned for life over doping convictions.

Among the athletes undergoing training were Olga Kaniskina and Sergey Kirdyapkin, both of whom had been stripped in March of their Olympic medals because of doping.

Based on documents of the former boss of the anti-doping laboratory in Moscow, Grigory Rodchenkov, the whistle-blower who has fled to the United States, ARD noted that Russia's sports ministry advisor Natalia Zhelanova was "permanently interfering (in the) everyday operation of anti-doping agency Rusada".

A previous ARD documentary, titled "Secret Doping Dossier: How Russia produces its Winners" and broadcast in December 2014, first brought Russia's doping scandal to light.

It has also sparked investigations that led to a raft of Russian athletes being stripped of their Olympic medals.

mp (AFP, DPA, SID)