Lance Armstrong could face a potential $150m (Dh500m) bill after the US justice department filed a formal complaint against the shamed cyclist for fraud.
The US government is seeking triple damages in a jury trial after accusing the disgraced Tour de France and Olympic cyclist of defrauding the US Postal Service of sponsorship cash.
The government, which said in February that it would join a whistle-blower lawsuit brought by former Armstrong teammate Floyd Landis in 2010, says the USPS spent about $40 million in sponsor money and gave Armstrong $17 million.
Armstrong admitted during an interview with Oprah Winfrey earlier this year that he used performance-enhancing drugs during his Tour de France victories - having been stripped of those titles following a US Anti-Doping Agency (USADA) investigation.
The US government's involvement in the complaint means Armstrong could now face a potential bill of $150m if he loses the case.
"Riders on the USPS-sponsored team, including Armstrong, knowingly caused material violations of the sponsorship agreements by regularly and systematically employing banned substances and methods to enhance their performance," the complaint states.
"Defendants were unjustly enriched to the extent of the payments and other benefits they received from the USPS, either directly or indirectly."
However Elliot Peters, Armstrong's attorney, said there was a dispute over whether the USPS suffered any damage as a result of its 1998-2004 sponsorship of the cyclist's tea,
"The DOJ's complaint against Lance Armstrong is opportunistic and insincere," he said.
"The US Postal Service benefited tremendously from its sponsorship of the cycling team. Its own studies repeatedly and conclusively prove this. The USPS was never the victim of fraud."
"Lance Armstrong rode his heart out for the USPS team and gave the brand tremendous exposure during the sponsorship years."
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