Merlene Ottey, the most successful female athlete in World Championship history, withdrew from those championships in Seville yesterday after testing positive for nandrolone.

The Jamaican sprinter joins Britain's Linford Christie and Dougie Walker in the dock after testing positive for an anabolic steroid which has become the sport's most controversial issue.

The 39-year-old Ottey, winner of a record 34 major championship medals, tested positive after a meeting in Lucerne on July 5th. She was informed of the result on Monday. The B sample has still to be tested and until then she is officially free to compete. But Ottey, one of only four athletes to have competed in all six world championships, pulled out immediately.

In a statement Ottey said: "To write this has been the most difficult and emotionally draining experience of my life. I have lived my personal and athletic life with the utmost honesty and integrity. I have applied only the highest ethical standards to myself and expect the same from others. I have always proclaimed fairness in sports and adamantly oppose all use of banned substances.

"I owe it to my family, my country, my beloved sport and all my fans around the world to prove that this is a terrible mistake and that I will do everything in my power to find the truth and prove my innocence."

She added that she would have a voluntary test carried out immediately.

During an international career, which began when she finished third in the 200 metres at the 1979 Pan Am Games, Ottey has become one of the world's most popular athletes. Since competing in the first world championships in Helsinki in 1983 she has won a record 14 world medals, including three golds from the 200 metres in 1993 and 1995 and the 4x100 metre relay in 1991; she has never been outside the top three in the 200 metres.

But an Olympic gold has always eluded Ottey. She finished third in the 200m at Moscow in 1980, the first of seven silver or bronze medals. She suspected she had suffered at the hands of athletes who were using performance-enhancing substances.

Ottey had planned to carry on until the Sydney Olympics next year, when she would be 40. The two-year ban which is on the cards would obviously throw that dream into tatters.

Jamaica will be shocked by the news. She was voted the country's sports personality of the year 15 times between 1979 and 1997 and, as an official ambassador for the island, travels on a diplomatic passport.

Parallels will inevitably be drawn between this case and Christie's. The pair have always been good friends and the Jamaican-born Christie briefly coached Ottey.

"It's a personal shock to me," said Istvan Gyulai, secretary of the International Amateur Athletic Federation. "It is sad, it is disappointing that at a rather mature age some athletes probably believe this is the way to continue to be in centre stage."

This case, and the IAAF's decision to refer Walker's case to an arbitration panel, will again focus attention on those who have tested positive for nandrolone. These have included over the past two years four French league footballers, including the World Cup-winning Christophe Dugarry, the Olympic judo champion Djamel Bouras, also from France, and Petr Korda, the 1998 Australian Open tennis champion.

Others have escaped punishment. Paola Pezzo of Italy, the Olympic and World Champion mountain biker, and the Dutch cyclist Yvonne Brunen were cleared after claiming nandrolone could be generated naturally by women.

Olivier Bernhard, a Swiss triathlete, successfully argued that nandrolone could occur following strenuous exercise.