It may require years of legal argument and enormous financial cost, but Lance Armstrong could yet be forced into court on charges that he lied when he denied ever using performance-enhancing drugs.

The 41-year old former cyclist, whose seven Tour de France wins and cancer charity made him a global icon, is accused of being at the heart of sport's "most sophisticated, professionalized and successful doping program."

Armstrong has always maintained that he did not use banned substances during his career, but in August he chose not to contest charges put forward by the US Anti-doping Agency (USADA) that he was a serial drugs cheat.

Although fingers were pointed at Armstrong for years, cycling's governing body, the International Cycling Union (UCI), has never sanctioned him and it has since been suggested that some officials looked the other way.

But it is the sheer and unprecedented volume and detail of allegations that the USADA published this week that could lead US prosecutors and companies to consider fresh criminal and civil actions, experts said Friday.

One possibility is that justice officials in California will re-open a file they closed earlier this year concerning alleged drug use and misuse of funds when Armstrong was with the government-funded US Postal Service team.

Peter Keane, a law professor at Golden Gate University in San Francisco, said the new evidence -- including testimony from Armstrong's team mates that they saw Armstrong inject himself with banned drugs -- may force the u-turn.

"The Justice Department is coming under a lot of pressure to take action. I am sure they are taking a second look at anything Armstrong was involved in," said Keane, whose expertise includes criminal procedure.

"The USADA report has re-opened a number of problems for him."

Another case that could return to haunt the fallen icon is an arbitration hearing in Dallas in 2005 where he said on oath that he had never taken banned substances, a statement which raises the specter of possible perjury charges.

Armstrong had taken the stand to contest an insurance company's decision to refuse to pay him a $5 million bonus -- for achieving five consecutive Tour de France wins -- on account of widespread media rumors that he was doping.

The cyclist eventually received a settlement totaling $7.5 million, but the company concerned, SCA Promotions, is closely monitoring the situation.

"At this time, SCA will await the UCI's response to the USADA report, and once the UCI decides what course of action it will take, we will assess our legal options," Jeffrey Dorough, a lawyer for SCA, told AFP.

While the evidence against Armstrong appears damning, there are substantial hurdles to any legal action, civil or criminal, being taken.

A major factor is that the California case is seen as highly political: any decision to prosecute would be taken by the US Attorney General in Washington.

The fact that Armstrong is a cancer survivor whose later feats confounded the expectation that he would die in his twenties, is also relevant, said Jordan Kobritz, chair of the Sports Management Department at SUNY Cortland.

"There's no political upside for President Barack Obama, or for possible president Mitt Romney, of re-opening that investigation," said Kobritz, who also highlighted the millions of taxpayer dollars it would cost.

"The majority of the public still regard Lance Armstrong as a successful person and someone who raised around $500 million to fight cancer," he added, noting the persuasive effect that could have on a jury.

There are also potential problems with pursuing an appeal over the Dallas arbitration ruling, given that parties to such civil hearings agree at the outset to accept the outcome as final, unless there is fraud in the process.

Meeting the latter requirement would be tough, but the contradictory nature of the USADA report, could lead to a review or fresh lawsuit from SCA, said Michael Straubel, professor of law at Valparaiso University, in Indiana.

"They will be examining the evidence closely and seeing how they can re-open the proceedings," said Straubel, who has represented athletes accused of doping offenses and is a widely-published author on the subject.

[Images via Agence France-Presse]