A lawsuit challenging the Bush administration's terrorist surveillance program must be dismissed because it threatens to reveal state secrets and jeopardize the War on Terror, the government says.

The case was set to go before a federal judge in San Francisco on Friday.

The Bush administration argues that the courts cannot decide the constitutionality of the president's asserted wartime powers to eavesdrop on Americans without warrants.

The government is invoking the so-called "state secrets privilege" in a federal lawsuit filed by a privacy group against communications giant AT&T Inc. about the telecom's alleged involvement in Bush's surveillance program adopted after the Sept. 11, 2001, terror attacks.

"Resolution of those legal issues depends entirely on facts that, in light of their highly classified nature, cannot be made the subject of litigation," the Justice Department wrote in a brief to U.S. District Judge Vaughn Walker.

The legal tactic of state secrets privilege, first recognized by the U.S. Supreme Court in a McCarthy-era lawsuit, has been increasingly and successfully invoked by federal lawyers seeking to shield the government from scrutiny by the courts, from espionage cases and patent disputes to routine employment discrimination lawsuits.

The president confirmed in December that the National Security Agency has been conducting warrantless surveillance of calls and e-mails thought to involve Al Qaeda terrorists if at least one of the parties to the communication is outside the United States. The administration is mum on whether purely domestic calls and electronic communications are being monitored, as the lawsuit alleges.

The lawsuit was brought by the Electronic Frontier Foundation, on behalf of customers of San Antonio-based AT&T. The EFF accuses the telecom of illegally cooperating with the NSA to make communications on AT&T networks available to the spy agency without warrants.

AT&T said it follows all applicable laws when it comes to government monitoring of customer data, but would neither confirm nor deny the allegations.

The EFF is urging Walker in legal filings to rule on whether the president possesses wartime powers to authorize warrantless eavesdropping in the United States without publicly disclosing any classified or sensitive material.

The U.S. Supreme Court upheld the state secrets defense as recently as January, when it rejected an appeal from a former covert CIA officer who accused the agency of race discrimination. And last month, citing the state secrets defense, the government urged a federal judge in Virginia to block a lawsuit by a German national who says he was illegally held in a CIA-run prison in Afghanistan for four months and tortured.

The Supreme Court first recognized the state secrets doctrine in 1953, when it dismissed a lawsuit against the government brought by family members of people killed in a plane wreck while testing secret electronic surveillance equipment.