US prosecutors said Friday they had dropped their investigation into seven-time Tour de France champion Lance Armstrong and other cyclists without bringing criminal charges.

A statement by US attorney Andre Birotte jnr said Birotte's 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."

The probe has reportedly included a grand jury sitting in Los Angeles hearing testimony from former Armstrong teammates and associates.

Although such grand jury procedings are supposed to remain secret, the investigation has been widely reported on, prompting Birotte's office to take the step of announcing it had ended.