Federal prosecutors say they are closing a criminal investigation of Lance Armstrong and will not charge him over allegations the seven-time Tour de France winner used performance-enhancing drugs.

In a statement, United States Attorney Andre Birotte Jr said the case had been closed but didn’t disclose the reason for the decision.

Investigators looked at whether a doping program was created to keep Armstrong and his team-mates running at the head of the pack while, at least part of the time, they received government sponsorship from the US Postal Service.

Armstrong won the Tour de France every year from 1999-2005 and has always fiercely denied doping.

Prosecutors, however, began presenting evidence almost two years ago to a federal grand jury in Los Angeles, and several of Armstrong’s former team-mates and associates provided testimony.

The US Attorney’s statement said: “United States Attorney Andre Birotte Jr today announced 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.

“The United States Attorney determined that a public announcement concerning the closing of the investigation was warranted by numerous reports about the investigation in media outlets around the world.

“Mr Birotte commended the joint investigative efforts of his prosecutors and special agents with the US Food and Drug Administration, the Federal Bureau of Investigation and the United States Postal Service – Office of the Inspector General.”