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The validity of long-standing world records in athletics has again been called into question after governing body the IAAF confirmed it was investigating claims China's double world record holder Wang Junxia admitted to doping.
According to Chinese state media, Wang, who remains the world record holder for the 3,000 and 10,000 metres, admitted being an unwilling participant in a state-sponsored doping programme.
The claims are contained in a letter allegedly written in 1995 by Wang and nine team-mates coached by the controversial Ma Junren, but has only just come to light.
Junren's athletes, who were known as Ma's Army, won every women's gold medal from 1500m to 10,000m at the 1993 World Championships in Stuttgart.
The legitimacy of Wang's world records, set in the space of six days in Beijing in 1993, has long been questioned. Her 10,000m record of 29 minutes 31.78 seconds knocked 42 seconds off the old record and is still 22 seconds faster than any other woman has run.
The letter, sent to a journalist named as Zhao Yu, reportedly revealed that Ma's athletes were forced to dope and, when they started to throw away the illegal drugs over fears for their health, they were injected personally.
"We are humans, not animals," the alleged letter's authors wrote.
"For many years, (he) forced us to take a large dose of illegal drugs. It was true."
The IAAF confirmed it was looking into the letter and said any athlete proved to have admitted to doping before achieving a world record could be stripped of the title.
It said in a statement: " The IAAF's first action must be to verify that the letter is genuine. In this respect, the IAAF has asked the Chinese Athletics Association to assist it in that process. In any case, IAAF Competition Rule 263.3 (e) note (ii) clearly states that if anyone makes an admission of guilt, the IAAF can take action:
"If an athlete has admitted that, at some time prior to achieving a world record, he had used or taken advantage of a substance or technique prohibited at that time, then, subject to the advice of the medical and anti-doping commission, such record will not continue to be regarded as a world record by the IAAF."
Wang, who won 5,000m gold at the Atlanta Olympics in 1996, is a member of the IAAF Hall of Fame. The 43-year-old retired in 1997, having never failed a drugs test.
Ma himself has consistently denied using performance-enhancing drugs.
Last month UK Athletics called for world records to be reset due to the doping crisis which has engulfed the sport.