AUSTIN, Texas - The Justice Department is joining a lawsuit against Lance Armstrong Tuesday, saying he was "unjustly enriched" while cheating to win the Tour de France.
The suit also said Armstrong violated his contract with the U.S. Postal Service.
The government had previously announced it would join the whistle-blower lawsuit brought by former Armstrong teammate Floyd Landis. Tuesday was the deadline to file its formal complaint.
The Postal Service paid about $40 million to be the title sponsor of Armstrong's teams for six of his seven Tour de France victories. The lawsuit says the USPS paid Armstrong $17 million form 1998-2004.
An Armstrong attorney says the Postal Service made money off the cyclist and called the federal complaint "opportunistic and insincere."
Armstrong admitted in January to using performance-enhancing drugs to win.
The lawsuit also names former team Armstrong team director Johan Bruyneel and team management company Tailwind Sports as defendants.