Lance Armstrong said he was "gratified" the US attorney's office had decided not to bring charges against him after a nearly two-year investigation into whether the champion cyclist and his teammates ran a doping programme.

Armstrong released a statement hours after US Attorney Andre Birotte announced the investigation was closed.

The seven-time Tour de France winner said it was "the right decision", adding: "I look forward to continuing my life as a father, a competitor, and an advocate in the fight against cancer without this distraction."

Armstrong has steadfastly denied taking drugs during his unparalleled career, but the possibility of criminal charges threatened to stain his legacy as the world's greatest cyclist and could have cast a shadow over his cancer charity work.

"This is great news," his lawyer Mark Fabiani said. "Lance is pleased that the United States Attorney made the right decision, and he is more determined than ever to devote his time and energy to Livestrong and to the causes that have defined his career."

The probe, anchored in Los Angeles where a grand jury was presented evidence by federal prosecutors and heard evidence from Armstrong's former teammates and associates, began with a separate investigation of Rock Racing, a cycling team owned by fashion entrepreneur Michael Ball.

Mr Birotte announced in a press release that his office "is closing an investigation into allegations of federal criminal conduct by members and associates of a professional bicycle racing team owned in part by Lance Armstrong".