Lance Armstrong could be forced to testify under oath about his doping after a US insurance firm filed a lawsuit Thursday demanding the disgraced US cyclist return $12 million (RM37 million) in bonus money payments.

Texas-based SCA Promotions paid the now admitted dope cheat bonus money for his Tour de France triumphs after insuring his victories and wants him to repay it because he was stripped of his record seven Tour titles last year.

"It is time now for Mr Armstrong to face the consequences of his actions. This includes returning all of the funds paid to him by SCA, which totals more than $12 million," the lawsuit said.

"Mr Armstrong has no legal right to retain any prize money paid to him by SCA because he is not the official winner of any Tour de France titles."

The 35-page state court filing in Dallas would deliver a financial blow as well as put Armstrong under oath about the doping scandal that ruined his cancer-comeback story and tainted his Livestrong Foundation charity work.

"Lance Armstrong perpetuated what may well be the most outrageous, cold-hearted and elaborate lie in the history of sports," the lawsuit said.

Armstrong was banned for life when the US Anti-Doping Agency found overwhelming evidence that he was at the heart of a sophisticated doping scheme when his US Postal Service team dominated the Tour de France.

"Even Lance could not cycle up the mountain of evidence gathered by USADA," the lawsuit said.

After years of what the lawsuit called a "wall of deceit", Armstrong confessed last month to US talk show host Oprah Winfrey that he had taken performance-enhancing drugs in sweeping Tour titles from 1999 to 2005.

Armstrong had previously sued SCA and won after the firm delayed his 2005 bonus payment because of reports the American had used performance-enhancing drugs.

"We think there are several avenues for us to seek recovery on this," SCA attorney Jeff Dorough told AFP.

"Armstrong and his lawyers said flat out at that time that if he was ever stripped of the titles, they would pay the money back," Dorough said. "We're just seeking to hold them to their promises."

Armstrong attorney Mark Fabiani cited details of a 2006 settlement agreement between SCA and Armstrong in saying that the firm had no recourse to reclaim the money.

"We are going to let the settlement agreement speak for itself. It is very clear on this point," Fabiani told AFP. "The language of the agreement clearly bars SCA from wriggling out of the agreement."

The settlement, in which SCA agrees to pay Armstrong $7.5 million, says in part that "no party may challenge, appeal or attempt to set aside the arbitration award."

The lawsuit asks that the arbitration award be vacated because Armstrong lied under oath.

"While he lied to everyone, Lance Armstrong lied to SCA in shocking fashion: while testifying under oath in a legal proceeding," the court document said.

"His perjury went well beyond simply denying he used performance-enhancing drugs. Instead, he lied aggressively, repeatedly and without remorse under oath in an effort to create the aura that he was a 'clean rider.'"

The lawsuit also quotes Armstrong attorney Tim Herman as saying in the prior court case that, "if titles are stripped as a result of official action, then (Armstrong) agrees to refund any payments made."

"If the titles are stripped, then there's an obligation to return the money -- and we don't dispute that," Herman was also quoted as saying.

SCA wants Armstrong held to those statements.

"Now that he has been exposed and stripped of those titles, it is time to make him live up to what he said," the lawsuit said.

Armstrong also faces a lawsuit from former US Postal teammate Floyd Landis, who was stripped of the 2006 Tour de France title for doping but says Armstrong violated terms of a sponsorship deal with US Postal by using banned drugs.

ABC News has reported that federal agents are investigating Armstrong for crimes including obstruction of justice, witness tampering and intimidation.

USADA chief Travis Tygart has communicated with Armstrong and given him until February 20 to testify under oath about his activities for a hope of reducing his ban to permit entry into sanctioned cycling and triathlon events.

"We understand that he does want to be part of the solution and assist in the effort to clean up the sport of cycling," Tygart said.