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A former personal assistant to Lance Armstrong (search) filed court papers Thursday alleging that he discovered a banned substance in the six-time Tour de France winner's apartment early last year.

Mike Anderson (search), who is involved in a legal fight with Armstrong over alleged promises the cyclist made to help Anderson start a bike shop, made the claim in a brief filed in state district court. The brief does not say whether Anderson saw Armstrong take any banned substances.

Armstrong, who has won a record six consecutive Tours, has maintained that he is drug-free. The cancer survivor frequently notes he is one of the most drug-tested athletes in the world.

A representative for Armstrong referred all questions to the cyclist's attorney, Timothy Herman, who declined immediate comment because he hasn't seen the brief. Armstrong is in Europe, where he finished 24th at the Paris-Camembert race (search) Tuesday.

Anderson, who says he had a key to Armstrong's apartment in Girona, Spain, alleges he was cleaning the bathroom in "early 2004" when he found a white box labeled "like any other prescription drug" but that did not have a doctor's prescription attached.

Written on the box was the trademark name "Androstenine, or something very close to this," Anderson said.

"He went to the computer, looked it up on the WADA or USADA Web site(s), and confirmed that what he had found was an androgen, a listed banned substance," Anderson's court brief states, referring to the World Anti-Doping Agency (search) and the U.S. Anti-Doping Agency (search).

Anderson said he put the box back where he found it. Fearing he would be fired, he said he did not confront Armstrong about it. He said he looked for the box again after Armstrong left Girona to train in the Canary Islands, but didn't find it.

"He was torn about what to do. He's an honest guy opposed to doping in sports," said Anderson's attorney, Hal Gillespie. "(But) he was sure that if he confronted, he would be fired. He's got a wife and young child, no money and a long way from home."

Gillespie said Anderson did not see Armstrong taking any steroids or other banned substances.

Anderson's brief also said he and Armstrong had a discussion in 2004 about cyclists who dope and claimed Armstrong told him, "Everyone does it."

Gillespie said that conversation took place before Anderson allegedly found the steroid. The lawyer also said he plans to depose Armstrong.

Anderson said he believes Armstrong knew about the alleged discovery because their relationship began to deteriorate almost immediately.

Anderson said he was working as a mechanic at a local bike store when he met Armstrong more than four years ago. They became friends, often riding together, and Anderson regularly worked on Armstrong's bikes before becoming his personal assistant in November 2002.

Anderson said he was paid about $3,000 a month for duties that ranged from building bike trails on Armstrong's Hill Country property to doing his grocery shopping in Spain. He says he developed a close relationship with Armstrong and his family.

Anderson said he was fired in November 2004 after asking for, and getting, a $500 a month raise. He said Armstrong's representatives offered him a severance package totaling $7,000.

Armstrong and his personal service company, Luke David LLC, sued Anderson about a month later, claiming Anderson demanded Armstrong pay him $500,000, give him a signed Tour de France jersey and future endorsements to help him set up his own bike shop.

Anderson countersued, accusing the cyclist of fraud, breach of contract and causing him severe emotional distress. Anderson says an e-mail Armstrong sent to offer him the job promised the help and should be considered a binding contract.

Anderson said Armstrong also demanded he sign a confidentiality agreement that would have held him liable for up to $1 million in damages.

Thursday's filing was because the court wanted more details in support of Anderson's claim.