Twenty-eight athletes have been suspended over historic doping offences, the International Association of Athletics Federations has announced.

The world governing body, under fire in the wake of allegations of widespread doping in the sport, said the retesting of anti-doping samples from the 2005 and 2007 World Championships in Helsinki and Osaka had turned up 32 adverse findings from 28 athletes.

The IAAF, which has come out fighting in the wake of the accusations in the Sunday Times and by German broadcaster ARD that it turned a blind eye to mass doping, said it could not name the athletes concerned “due to the legal process”.

It said: “A large majority of the 28 are retired, some are athletes who have already been sanctioned, and only very few remain active in sport. The IAAF is provisionally suspending them and can confirm that none of the athletes concerned will be competing in Beijing.”

This year’s World Championships get under way in the Chinese capital a week on Saturday.

The IAAF said that from April this year it had, using the latest anti-doping technology, again retested samples from Helsinki and Osaka. It pointed out this reanalysis had commended well before the latest allegations against the governing body.

The IAAF said these samples had been “proactively stored” at the Swiss Laboratory for Doping Analyses (LAD), the World Anti-Doping Agency-accredited laboratory in Lausanne.

It said it had already, in 2012, conducted a first round of reanalysis of urine samples taken from Helsinki, which had led to six adverse findings.

Before Tuesday’s announcement, nine athletes in total had been sanctioned following retesting of samples from various World Championships.

The IAAF said in a statement: “The IAAF embarked on this long-term storage and retesting strategy in 2005 to ensure that clean athletes are ultimately rewarded for their honest efforts in IAAF competitions. The IAAF is committed to use every means at its disposal within the world anti-doping code to root out the cheats, however long it takes.”

The IAAF said it would re-allocate medals where necessary should doping offences be confirmed.

The IAAF has been accused of not following up suspicious blood test results from hundreds of athletes, including major medal winners, in allegations based on the expert analysis of leaked data relating to 12,000 blood tests conducted on more than 5,000 athletes.

The claims threaten the already fragile reputation of the sport rocked by repeated drug scandals and have been vehemently denied by the governing body.

Lord Coe, who is standing for the presidency of the IAAF, branded the allegations a “declaration of war” on athletics, but the two experts who analysed the leaked data, Michael Ashenden and Robin Parisotto, have stood by their views and WADA announced an urgent investigation into the claims.

London Marathon chief executive Nick Bitel also hit out at the IAAF, while some athletes have also made public their anger, with Olympic discus champion Robert Harting leading a group of German athletes in criticising the organisation in an online video.

Harting said: “Dear IAAF, we can not trust you any more.”