Retests from World Championships in 2005 and 2007 have led to the suspension of 28 athletes from the IAAF.
The International Association of Athletics Federations (IAAF) has suspended 28 athletes suspected of doping at the 2005 and 2007 World Championships.
Initial tests in 2012 resulted in nine athletes from the two Championships being suspended, with a second analysis of urine samples now throwing up 32 adverse findings.
The IAAF is unable to name the athletes for legal reasons, although many are now retired.
Those who remain active will be unable to compete in this year's Championships in Beijing.
An IAAF statement pointed out that the investigations had started before a doping crisis that is currently overshadowing much of athletics.
The organisation has been embattled in recent weeks after a documentary by German broadcaster ARD and subsequent report from British newspaper The Sunday Times claimed wide-scale doping was prevalent in the sport.
Both ARD and The Times claimed to have obtained a database containing 12,000 blood tests of around 5,000 athletes from 2001 to 2012, which the IAAF insist was obtained illegally.