The seven-time Tour de France winner Lance Armstrong says he's prepared to co-operate in an investigation into alleged doping fraud by his former team US Postal as long as it doesn't become a witch hunt.
Armstrong's participation on this year's tour has been hampered by further doping allegations by former team-mate Floyd Landis.
Landis was stripped of his Tour winner's yellow jersey in 2006 after testing positive for testosterone and spent four years and millions of dollars trying to clear his name before confessing to doping two months ago.
Along with his confessions, however, were claims that Armstrong and several other riders in US Postal were involved in doping practices, allegations Armstrong denies.
The New York Times says US authorities have issued grand jury subpoenas to potential witnesses, and Armstrong says he'll co-operate as long as the investigation is legitimate, credible and fair.
Accusations of doping have followed Armstrong throughout his career, although he's never tested positive.
