(File image) Lance Armstrong

Los Angeles - The United States Anti-Doping Agency (Usada) has filed a motion asking a judge to dismiss Lance Armstrong's federal lawsuit that seeks to prevent the drug-fighting organisation from pursuing doping charges against him.

The motion, filed on Thursday in Austin, Texas, cites the Ted Stevens Amateur Sports Act, which gives Usada jurisdiction over athletes who compete in Olympic sports.

It also includes a 2005 affidavit from Usada CEO Travis Tygart stating that Armstrong took part in Usada's testing programme and was under its jurisdiction - the opposite claim Armstrong is making in the current case.

The affidavit helped bolster Armstrong's claims in a lawsuit against SCA Promotions, which refused to pay bonus money to the Tour de France winner because of allegations he used performance-enhancing drugs. - Sapa-AP