The inquiry was sparked by official protests from the Australian and New Zealand teams, claiming that the unnamed athlete was duping organisers of the World Veterans Athletics Championships being held this week in Gateshead, Tyne and Wear.
The athlete in question will now have a blood test to prove gender, but will be able to continue to compete until the results are known, Torsten Carlius, president of the World Association of Veteran Athletes (WAVA) said: "Until the verdict is announced the athlete can compete in her remaining events." Organisers said that the athlete will not be identified while the results are pending.
More than 6,000 athletes are taking part in the championships at the Gateshead International Stadium with teams from 74 nations taking part. Woman above 35 years and men over 40 can compete.