A Russian race walker stands to lose his gold medal from the 2012 London Olympics after the Court of Arbitration for Sport on Thursday rejected the selective punishments imposed by Russian authorities in six doping cases.

The Switzerland-based court ruled that the Russian anti-doping agency, known as RUSADA, had wrongly imposed bans which were timed in a way that the six athletes' results were not annulled and allowed them to keep major titles.

Russia will also lose an Olympic silver medal and two world championship gold medals as a result of the CAS decision.

Track and field's world governing body, the IAAF, said it "will immediately proceed to the effective disqualification of results" from its competitions and ask the IOC to reallocate Olympic medals. The ruling was "in the interest of clean athletes and sport justice," the IAAF added.

Sergei Kirdyapkin is set to be stripped of his Olympic gold medal in the 50-kilometre walk. The medal stands to go to Australia's Jared Tallent, subject to ratification by track and field's governing body and the International Olympic Committee.

"I'm just very, very happy to know that I am rightfully and will be officially named as the Olympic champion from London," Tallent told The Associated Press by telephone. "It's something that I felt on the day and ever since when I raced. This is a victory for clean athletes."

Tallent said the Australian Olympic Committee had told him it expects the IOC to formally change the result in June. He said he has been promised his own medal ceremony, four years late.

China's Si Tianfeng would move up to silver, with bronze for Ireland's Rob Heffernan.

The six cases before CAS were based on the biological passport system, which tracks unusual blood values for signs of doping.

'Selective' judgement

RUSADA had argued that its suspensions applied only to times when the athletes' blood values were extreme, but the IAAF appealed, saying that the timing of the bans was "selective."

In Kirdyapkin's case, RUSADA had allowed him a window of four months in 2012 which meant he kept an Olympic gold medal which he would otherwise have lost.

CAS, however, ruled that all of Kirdkyapkin's results from August 20, 2009, to Oct. 15, 2012, were now disqualified. That covers the London Olympics, which took place in July-August 2012.

Also affected by the CAS ruling is Olga Kaniskina, who stands to lose her silver medal in the 20K walk from the London Olympics. China's Qiejang Shenjie would move up to silver.

Russia is also set to lose two gold medals from the 2011 world championships in Daegu, South Korea — Yulia Zaripova in the 3,000-meter steeplechase and Sergei Bakulin in the 50K walk. Zaripova's gold would go to Tunisia's Habiba Ghribi; Bakulin's medal to fellow Russian Denis Nizhegorodov.

CAS said reallocation of medals is up to the IAAF. CAS also imposed disqualifications on walkers Valery Borchin and Vladimir Kanaikin.

Russia accused of cover-up

Russian reaction to the decision was muted. Sports Minister Vitaly Mutko said the CAS ruling was "an issue from last year already, a closed issue" in comments to R-Sport.

Maxim Saushkin, a spokesman for the Russian state-run training centre where five of the six walkers were based, said there would be no comments from the athletes or their representatives until they received "the relevant documents" confirming the ruling.

The acting head of RUSADA, Anna Antseliovich, told the AP that she stood by her agency's original decision to allow the six athletes to keep certain results, but that she would respect the CAS verdict.

"We presented our experts' opinions at CAS. We believe the decision had been imposed properly, but the CAS arbiters found that the IAAF position was stronger and more convincing," she said. "We'll take it into account when RUSADA takes decisions, but each case is individual."

RUSADA was suspended from conducting any testing in November 2015 after a World Anti-Doping Agency commission accused it of covering up doping among leading Russian athletes.

Of the six athletes in the case, four have since become eligible to compete again, and some say they want to compete at the Olympics in Rio de Janeiro in August. However, Russia remains suspended from all international track and field, including the Olympics, after the WADA commission's report detailed state-sponsored, systematic drug use. Doping in race-walking is a particular concern for the IAAF, after more than 30 cases in Russia in recent years.

"The Russian athletes are definitely getting what they deserved," Tallent said, adding that "it'll be a dark day for the sport" if Kirdyapkin is allowed to race in Rio.

"Once you're a cheat and you're caught, you should never be allowed to compete again. You should be banned for life," Tallent said. "I hope that Russia is still excluded."

Kirdyapkin and Bakulin face possible further charges over allegations that they continued to race while they were supposed to be suspended. Kaniskina also worked as director of a major training centre while serving a suspension.