Retesting results in 28 bans

The IAAF, the governing body for world track and field, has initiated disciplinary action against 28 athletes after it retested samples from the 2005 and 2007 world championships with new technology that can uncover previously undetectable substances.

The retests revealed 28 adverse doping cases - primarily Russians and Eastern Europeans, according to sources that requested anonymity.

The sources were not aware of any Americans on the list and the BBC reported there were no British athletes.