London  - Disgraced British sprinter Dwain Chambers admits in his forthcoming autobiography "Race Against Me" that he took a concoction of over 300 performance-enhancing drugs.

In an instalment published in Tuesday's Daily Mail ahead of next Monday's release, Chambers, who served a two-year ban after being found guilty of doping offences in
2003, said he had paid out 30,000 dollars a year for doping substances.

"I wasn't just on THG, EPO and HGH, but testosterone to help with sleep and reduce cholesterol," he said. "On Christmas Day (in 2002), as I sat in the bathroom with 'The Clear' (THG), I realized I had been taking drugs - more than 300 different concoctions - for 12 months."

During that time, Chambers says he passed 10 doping tests as well as winning the 100-metre gold medal at the 2002 European Championships. However, his times hadn't improved that dramatically and he was also often troubled by stomach cramps.

"When I was clean, my personal best was 9.97 seconds. A year on, after the sleepless nights, the anxiety, the pain of the cramps, the blood draws to make sure I wouldn't suffer a stroke, or worse, the inconsistent races and the disappointment of missing events, my PB (personal best) was 9.87 seconds," he wrote.

Chambers, the first athlete with connections to BALCO founder Victor Conte to test positive for the previously undetectable steroid THG, was banned for two years after failing the 2003 dope test.

Following his admission that he doped, Chambers was stripped of his 100m European Championship gold medal as well as the gold Great Britain won in the 4x100m relay.

On returning from his ban Chambers qualified for the 2008 Olympics but the British Olympic Association (BOA) banned the 30-year-old from competing at future Games over his failed test.

Although Chambers was unsuccessful in a subsequent court bid to overturn the ban, he is due to compete for Great Britain this weekend at the European indoor championships in Turin, Italy, and also hopes to compete at this summer's world athletics championships in Berlin. (dpa)