The world athletics task force that holds the fate of Russia’s track and field athletes in its hands ahead of the Rio Olympics has said new doping allegations that implicate the sports minister Vitaly Mutko are a “grave concern” and will be investigated as a “matter of urgency”.

As the Russian authorities continue to try to prove they are serious about tackling the systemic doping issues outlined by an independent Wada report, a new documentary by the German broadcaster ARD will claim on Wednesday night that Mutko blocked the reporting of a doping offence by a top-flight footballer. It is believed that the positive test in question was never made public. The new revelations could be particularly damaging for Russia because they threaten to drag football into the debate for the first time before the country’s hosting of the 2018 World Cup.

Mutko did not respond when asked by the broadcaster whether he had ever intervened in the publication of a positive drug test.

In a statement last night the Russian Ministry of Sport said it “firmly rejects the allegation that it has failed to take the necessary steps to reform its anti-doping operations”, adding: “We understand that tackling doping is a huge challenge that will take time and significant change across Russia but we are working tirelessly towards long-term reform.”

The ministry said “a road-map with Wada” had been agreed under which the testing of Russian athletes is carried out in full by the UK Anti-Doping Agency. “In addition, we fully support and are implementing the recommendations of the IAAF’s expert group. Every Russian athlete will be subject to three additional doping tests by the IAAF.”

The new documentary from Hajo Seppelt, whose earlier revelations led directly to Wada commissioning a report from Dick Pound that laid bare the extent of cheating and corruption in Russia and at the International Association of Athletics Federations, will also allege that the Russian government was directly involved in covering up state controlled doping. Earlier this year, Seppelt secretly filmed a supposedly banned Russian coach still training athletes and the new programme will contain further footage of coaches who had supposedly been banned for life coaching top athletes.

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The IAAF task force, led by the respected Norwegian anti-doping expert Rune Andersen, asked for more time to complete its investigation in March and will now deliver its verdict on 17 June on whether Russia has met the tests set when the country’s athletes were banned by the IAAF in November.

In a letter to the programme makers dated 1 June, Andersen’s task force said their research was a “very serious matter” as well as a “matter of urgency” and represented a “grave concern”.

Even the IAAF’s decision on whether the Russian Athletics Federation returns to competition in time for the Games may not be the end of the matter, with the International Olympic Committee having signalled that it could be sympathetic to granting places to individual athletes who meet stringent criteria.

Meanwhile, the Canadian lawyer professor Richard McLaren is undertaking a separate independent review at the behest of Wada into claims by the former Moscow lab director Grigory Rodchenkov.