Lance Armstrong will not be charged over allegations that he used performance-enhancing drugs.

After two years of investigation, during which time Armstrong repeatedly denied ever doping, federal prosecutors have dropped a criminal investigation against the cycling star.

In a statement, Armstrong's lawyer Mark Fabiani said: "This is great news.

"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."

Armstrong won the Tour de France on seven occasions.