Russia's anti-doping body might soon face another ban over the massive 2015 doping scandal after a team sent by the World Anti-Doping Agency (WADA) was blocked from completing a key mission in Moscow.

The five-person team had arrived in Russia to obtain doping data from a Moscow lab's database. Russia previously agreed to share the data under a deal to lift a suspension of their anti-doping agency, RUSADA.

Following the team's arrival, however, the Russian side required WADA experts to use equipment "certified under Russian law."

"This issue had not been raised during an initial meeting on 28 November in Moscow, after which WADA sent its expert team back to Moscow to retrieve the data," WADA said.

The deadline to deliver the data is December 31.

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'Another shiv in the back'

In September, WADA reinstated RUSADA and announced a roadmap that Moscow would need to follow in order to stay in the international body. The move was sharply criticized by various anti-doping officials, including the head of US anti-doping agency, Travis Tygart, who called the decision to reinstate RUSADA "devastating blow to the world's clean athletes."

On Friday, Tygart appeared vindicated by the news that the WADA team was flying back empty-handed.

"Surprise, surprise - anyone shocked by this?" Tygart said. "Let's hope WADA leadership has finally learned the lesson and immediately declares them non-compliant."

Any other decision would be "another shiv in the back" of athletes who are not doping, Tygart added.

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Russia downplays dispute as 'technical'

WADA's account of the inspectors' Moscow visit seemed to clash with the statement made by Russian Sports Minister Pavel Kolobkov.

On Friday, Kolobkov told reporters that "WADA experts were satisfied with the visit" and that there were "some technical issues still left to resolve."

"I am convinced that we will come to an agreement," the minister said, adding that the team would soon make another visit to Russia.

"You will know everything by the end of December," Kolobkov said.

The global anti-doping agency said no further visits to Russia were planned, but added that its team "stands ready to proceed with the full data extraction should the matter be resolved by Russia expeditiously."

WADA's review committee is set to meet on January 14 to consider Russia's compliance with the September agreement. The body's executive committee would subsequently decide on reinstating the ban and any additional sanctions against RUSADA. The dispute could keep Russian athletes from competing under Russia's flag in the 2020 Tokyo Olympics.

Earlier this month, the world's track and field governing body refused to reinstate Russia until Moscow paid for the probe and provided WADA with the doping data.

dj/sms (AP, dpa, Reuters, Interfax)