Two of Lance Armstrong's former teammates have admitted to using performance-enhancing drugs during their careers.

The United States Anti-Doping Agency released a 1,000-page report on Wednesday accusing the US Postal Service team of running "the most sophisticated, professionalised and successful doping programme the sport has ever seen".

George Hincapie and Michael Barry have now confirmed that they were part of the alleged doping scheme.

"Early in my professional career, it became clear to me that, given the widespread use of performance enhancing drugs by cyclists at the top of the profession, it was not possible to compete at the highest level without them," Hincapie said in a statement.

"I deeply regret that choice and sincerely apologize to my family, teammates and fans."

Both Hincapie and Barry testified against Armstrong during USADA's investigation.