SAN FRANCISCO – The Justice Department urged a federal judge yesterday to force two San Francisco Chronicle reporters to testify about their sources for stories about a grand jury investigation into steroid use by professional athletes.

Prosecutors from Los Angeles assigned to investigate leaks of grand jury testimony asked Judge Jeffrey White to reject a motion from the reporters, Mark Fainaru-Wada and Lance Williams, to quash the subpoenas for intruding on newsgathering protected by the First Amendment.

“The criminal violations at issue here strike at the very heart of the secrecy of grand jury proceedings and the integrity of the judicial system,” the prosecutors said. “Under any scenario, this is no insignificant crime.”

In warning against recognition of a legal privilege against reporters’ testimony, prosecutors cited the proliferation of “reporter-bloggers.” Allowing such individuals to claim privilege from testifying to a grand jury would allow government officials and others to “readily and with impunity, engage in unlawful leaking of information through trusted friends or political operatives who would disclose the information to the public,” the prosecution team argued.

The prosecutors also dismissed arguments that the leaks led to reforms of drug testing rules for professional baseball. “The ‘leaked information’ served only to titillate and hold up to public ridicule those athletes who testified under the belief that their grand jury testimony would be ‘secret,'” the prosecutors wrote.

In a technical flub that has flummoxed the Justice Department before, the computer-generated filing yesterday used an ineffective method of blacking out the text of portions not to be released to the public. As a result, the redacted portions could be easily read by copying them into a word processing program.

Those portions detail e-mail correspondence between Mr. Fainaru-Wada and the founder of a drug lab implicated in the probe, Victor Conte Jr. According to the filing, Conte broached the possibility of giving the reporter a CD containing grand jury transcripts, but added “Just Kidding.” Mr. Fainaru-Wada pursued the possibility and suggested moving the conversation to a “pay phone or cell or even meeting that would provide more comfort.” Three days after that exchange in June 2004, the Chronicle published a story detailing testimony about steroid use by a sprinter, Tim Montgomery.

Conte, who pleaded guilty last year to steroid distribution charges, signed a court declaration denying any involvement in a leak. His attorney, Robert Holley, did not return a call last night.