Russian athletes are expected to be among 31 individuals who could be banned from the Rio Olympics after their samples from the 2008 Beijing Games tested positive for prohibited substances, putting the country’s participation in Brazil under further scrutiny.

The International Olympic Committee has announced that 31 Olympians from 12 countries, spanning six sports, are set to be banned from competing at Rio after retrospective target testing on urine samples from 2008. The IOC has suggested entire federations could be banned from the Games as the fight against doping is escalated, with president Thomas Bach warning it could represent a “shocking new dimension in doping”.

Russia, found last year by the World Anti-Doping Agency to have been running a state-sponsored doping programme, is already at serious risk of having no track and field representation at the Olympics this summer, while the findings from 250 further retrospective tests from London 2012 will be released later this month.

An International Association of Athletics Federations taskforce will decide on 17 June whether Russia’s athletes will be allowed to compete at the Rio Games. They are currently banned from international competition and any revelations of further positive tests would raise more questions about Russia’s position.

The IOC retested 454 samples from Beijing, using new anti-doping techniques that were not available at the time of the 2008 Games. They targeted athletes who are due to compete in Rio and around 7% of those tests came back positive.

The IOC will not identify the athletes in question until they have had the opportunity to request analysis of their “B” samples, although that process will be completed before the Olympics. It is understood a number of the 31 positives are from power and endurance events.

All 12 national Olympic committees whose athletes fell foul of the recent retrospective testing programme were due to be informed on Tuesday or Wednesday. The British Olympic Association said on Tuesday that it had not been contacted by the IOC and was not aware of any British athletes implicated.

The IOC will also undertake wider retrospective testing of medallists from Beijing and London, while samples from those athletes who could be promoted to medal status because of the disqualification of others will also be retested.

Bach said it would apply a “zero tolerance policy not only with regard to individual athletes, but to all their entourage within its reach”.

He added: “This action could range from lifelong Olympic bans for any implicated person, to tough financial sanctions, to acceptance of suspension or exclusion of entire national federations like the already existing one for the Russian Athletics Federation by the International Association of Athletics Federations.

“Should the investigation prove the allegations true, it would represent a shocking new dimension in doping with an, until now, unimaginable level of criminality.”

“The retests from Beijing and London and the measures we are taking following the worrying allegations against the laboratory in Sochi are another major step to protect the clean athletes irrespective of any sport or any nation.

“We keep samples for 10 years so that the cheats know that they can never rest. By stopping so many doped athletes from participating in Rio we are showing once more our determination to protect the integrity of the Olympic competitions, including the Rio anti-doping laboratory.”

Pressure on governing bodies from other sports to bar Russia from the Olympics has already grown after UK Anti-Doping revealed its testing mission in the country had been hampered by a number of obstacles. The agency has been given responsibility for testing in the country after Russia’s own anti-doping body was suspended. Of 247 tests overseen by Ukad in Russia from November last year to early this month, 99 were unable to be carried out because of an inability to locate an athlete and one test was refused.

Last week Dr Grigory Rodchenkov, a former head of the Russian Anti-Doping Agency, claimed that Russian urine samples during the 2014 Winter Olympics were switched from the main Sochi laboratory to a neighbouring shadow laboratory, allowing positive samples to go untested. Russia finished top of the medal table at its home Games with 33 in total and 13 golds.

The IOC has requested Wada conduct an investigation into the Sochi laboratory. A statement read: “The executive board of the IOC has requested Wada to initiate a fully fledged investigation into allegations that testing at the Sochi laboratory was subverted. The IOC for its part will instruct the Lausanne Anti-Doping Laboratory, where the Sochi samples are stored for 10 years, to proceed in cooperation with Wada with their analysis in the most sophisticated and efficient way possible.

“The IOC has already requested the Russian Olympic Committee to undertake all efforts to ensure the full cooperation of the Russian side in the Wada investigation. The IOC has put its medical and scientific director at the disposal of the Wada investigation. Based on the result of this investigation the IOC will take swift action.”

The Russian sports minister, Vitaly Mutko, said this week that the country was ashamed of cheating athletes but that anti-doping reforms were being established and banning Russia from the Olympics would be unfair.

“The Russian Ministry of Sport fully supports the IOC’s actions to protect clean athletes,” added a statement. “We are fully supportive of the decision that athletes who are doping, no matter what country they represent, should be punished and not be permitted to compete at competitions.

“However, we strongly believe that clean athletes, who have spent years of their lives training for the Games, should not be deprived of the right to participate. Moreover, we are willing to fully cooperate with Wada in their investigation and we have officially informed Wada of this.”

Meanwhile it was reported that the US Justice Department has opened an investigation into state-sponsored doping by dozens of Russian athletes.

The US Attorney’s Office for the Eastern District of New York is scrutinising Russian government officials, athletes, coaches, anti-doping authorities and anyone who might have benefited unfairly from a doping regime, the New York Times said.