The world athletics governing body, the IAAF has announced that 28 athletes from the 2005 and 2007 World Championships have returned "adverse findings" after re-testing of their samples.

Anti-doping cases have now been started against the athletes, following the re-tests, which were carried out before the end of the 10-year statute of limitations.

The IAAF has said that they are "provisionally suspending them".

The world governing body says that it intends to release the names of the athletes in question next week, but a large majority of the athletes are now retired with "very few" still active.

Some of the 28 have already been sanctioned for doping violations.