Lance Armstrong's lawyers say illegal government leaks of grand jury information have sullied the cyclist's reputation, and they have asked a US court to order federal agents to discuss their contacts with the media.

In a 20-page notice of alleged violations filed on Friday in the US district court in Los Angeles, lawyers for the seven-times Tour de France winner cited more than a dozen articles in media outlets from May 2010 to last month about a grand jury investigation into allegations Armstrong used performance-enhancing drugs in violation of US law. Armstrong has consistently denied using drugs.

The cyclist's lawyers argue that only someone in the government could be responsible for the leaks, and a judge should order the government to explain why it should not be held in contempt. In a last resort, the lawyers said, the court could force journalists to reveal their sources.

"The leaker in this case has, from the beginning, acted with the obvious intent of legitimising the government's investigation of a national hero, best known for his role in the fight against cancer," the court papers said. "Each leak has been designed to propagate public support for this investigation by smearing Armstrong and tarnishing his reputation. The tactical nature of these leaks cannot be ignored as it strongly suggests an underlying partisanship inherent in government agents."

Armstrong's lawyers accused the Associated Press, the New York Times, the Wall Street Journal, Sports Illustrated and CBS's "60 Minutes" of reporting illegally leaked information.

One of Armstrong's lawyers, John W Keker, attached a statement detailing 26 media reports about the alleged illegal leaks.

Responding to the notice, Lou Ferrara, AP's managing editor for sports, said: "The AP has been aggressive in covering this important story. AP reporters will continue to pursue the truth. This action will not stop us."