Lance Armstrong on Saturday shrugged off the US Anti-Doping Agency's decision to file formal doping charges against him, saying he wouldn't let it halt his cancer awareness work.

"I refuse to be distracted by @usantidoping's antics," the seven-time Tour de France champion wrote on Twitter, a day after the USADA announced it had filed the charges that could cost him his seven titles in the world's most prestigious cycling race.

"It's 2012, I'm gonna continue to lead @LIVESTRONG, raise my 5 kids, and stay fit!" Armstrong tweeted.

A three-member review panel evaluated evidence gathered by the USADA and a reply from Armstrong before unanimously voting to turn the allegations revealed on June 13 into formal charges.

The next step in the process will be a hearing before an arbitration panel. Its verdict could be appealed and the matter could be pushed to the Court of Arbitration for Sport (CAS) for a final resolution.

USADA claims it has witnesses to the fact that Armstrong and five former team associates - including Italian doctor Michele Ferrari and team manager Johan Bruyneel - engaged in a doping conspiracy from 1998-2011.

Armstrong, who won the Tour de France seven years running from 1999-2005 and used his fame to fuel his charitable work for anti-cancer causes through his Livestrong foundation, has never tested positive, and the 40-year-old US cycling legend has steadfastly denied any wrongdoing.

Armstrong would be allowed to review the USADA evidence in advance and cross-examine any witnesses against him.

Last week, in his 18-page reply to the USADA's allegations, Armstrong asked the review panel to dismiss the charges, saying the anti-doping group had not offered sufficient proof.

The review panel instead dismissed his position.

"All respondents will have the opportunity to exercise their right to a full public arbitration hearing, should they so choose, where all evidence would be presented, witness testimony would be given under oath, and an independent group of arbitrators would ultimately decide the outcome of the case," the USADA said in a statement.

(China Daily 07/02/2012 page23)