The coronavirus pandemic has been blamed for the delay.

Ustyugov and Sleptsova were given two-year bans after being found guilty of violating anti-doping rules by the International Biathlon Union's (IBU) Anti-Doping Hearing Panel.

The IBU found Ustyugov had taken oxandrolone and Sleptsova using ostarine.

As well as seeing all his results from August 27 in 2013 through to the end of the 2013-2014 World Cup season disqualified and facing a two-year year suspension, Ustyugov is set to lose his gold medal won at Sochi 2014.

The 35-year-old secured 4x7.5 kilometres relay gold at the Winter Olympic Games, meaning his team mates Anton Shipulin, Dmitry Malyshko and Alexei Volkov also face losing their medals.

CAS was scheduled to consider Ustyugov’s appeal on October 20.

Sleptsova is also appealing her lengthy suspension and the disqualification of her results from March 22 2013 through to the conclusion of the 2013-2014 World Cup campaign.

"The hearings in the CAS on the cases of Evgeny Ustyugov and Svetlana Sleptsova were postponed due to the difficult epidemiological situation," lawyer Alexey Panich told TASS.

"The dates of the new hearings have not yet been agreed."

Last month, Ustyugov told TASS he had spent  "hundreds of thousands" on legal fees challenging the IBU ruling, and claimed the Russian athletes found guilty of doping offences following analysis of the Moscow Laboratory data had been pre-judged.

"If it weren't for friends, you could have died of despair," Ustyugov said.

"I conducted many examinations, collected evidence, plus it is necessary to pay for the work of lawyers.

"This has already cost hundreds of thousands of dollars.

"Without influential friends, an ordinary athlete from Russia simply cannot fight with the soulless system of world sports, in our sport no one has such material resources.

"And the presumption of innocence was stripped of us long ago.

"The World Anti-Doping Agency (WADA) and the International Olympic Committee (IOC) have created a system in which, if they make a mistake, it is almost impossible to defend themselves."

It was reported by TASS that Ustyugov had undergone genetic tests to prove his innocence.

Ustyugov has also reportedly filed a lawsuit against the IBU in the Austrian state court after he was charged in a separate case by the Biathlon Integrity Unit (BIU).

The BIU charged Ustyugov because of abnormalities in his athlete biological passport in the period between January 2010 and February 2014.

Ustyugov is a two-time Olympic gold medallist, having won the mass start title at Vancouver 2010 and also picked up a relay bronze at those Games.

Sleptsova won an Olympic gold medal in the women's 4x6km relay in 2010.