'Lewis tested positive but still competed'

Carl Lewis heads the list of 19 American medallists who tested positive for drugs but were still allowed to compete at the Olympic Games in 1988.

The claim comes in the form of documents released by Dr Wade Exum, who was the director for drug control at the US Olympic Committee from 1991 to 2000.

Exum had planned to use the 30,000 pages of documents in a racial discrimination and wrongful termination suit against the USOC.

However, the case was dismissed last week because of lack of evidence.

The documents show that at a time when Americans were critical of methods supposedly used in Eastern Bloc countries, they had a doping problem of their own.

Lewis is often named as one of the greatest athletes of the 20th century after amassing nine gold medals in four Olympics.

He is also one of the world's most outspoken anti-doping campaigners.