Lance Armstrong finally admitted to doping on his way to seven Tour de France titles.

Washington – US federal justice officials are in the middle of an active criminal investigation of disgraced former Tour de France champion Lance Armstrong, ABC News reported on Wednesday.

The broadcaster cited an unnamed source saying agents are probing whether the US cyclist had ever obstructed justice or tampered with or intimidated witnesses – different charges than those previously looked at a federal level.

US Attorney Andre Birotte, who led a federal probe that was dropped last year, said on Tuesday he had no plans to press charges despite Armstrong's recent doping admissions, but he did not definitively rule out such action.

Birotte's investigation was centered on doping, fraud and conspiracy and Armstrong's denials of such crimes when he was the lead rider in the extremely successful government-funded US Postal Service Team.

“Obviously we've been well aware of the statements that have been made by Mr Armstrong and other media reports,” Birotte said, referring to Armstrong's bombshell doping confession to chat show legend Oprah Winfrey last month.

“That has not changed my view at this time. Obviously we'll consider – we'll continue to look at the situation,” Birotte told reporters in Washington.

The ABC News source, who the broadcaster quoted on condition of anonymity, said: “Birotte does not speak for the federal government as a whole. Agents are actively investigating Armstrong for obstruction, witness tampering and intimidation.”

Armstrong, however, faces other legal battles after being stripped last year of his record seven Tour de France titles.

Dallas insurance company SCA Promotions has already demanded the return of $12 million in bonuses it paid to the fallen Texas rider for achieving five consecutive Tour victories.

SCA attorney Jeff Dorough told AFP that the firm expected to file a lawsuit against the 41-year-old as early as Wednesday.

For years Armstrong denied doping, but he was banned last year after the US Anti-Doping Agency (Usada) gathered compelling testimony that he had been the ring-leader of a large-scale and highly-organized doping conspiracy. – Sapa-AFP