SAN FRANCISCO – A federal judge yesterday rejected a bid by AT&T to prevent one of its former employees from distributing information about an alleged secret arrangement through which the federal government has access to all data moving through the company’s Internet gateways on the West Coast.

The decision by Judge Vaughn Walker came at an initial hearing on a class-action lawsuit charging that AT&T broke the law and defrauded its customers by allowing the National Security Agency to install equipment to monitor e-mails, Internet traffic, and telephone calls. The case was brought in January on behalf of AT&T customers by a group devoted to preserving and advancing what it calls “digital rights,” the Electronic Frontier Foundation.

A former AT&T technician, Mark Klein, provided the group with a declaration and internal company documents that the foundation contends support its claims that AT&T is permitting the government unfettered access to Web traffic.

“He is saying they diverted the fiber optic cable and put it in a secret government room,” Mr. Klein’s attorney, James Brosnahan, told reporters. He said his client knew of special government taps on Internet data passing through AT&T hubs in San Francisco, Los Angeles, San Diego, San Jose, and Seattle.

It is not clear whether the so-called secret room Mr. Klein disclosed plays a role in what President Bush has described as a “terrorist surveillance program” to monitor international calls and e-mails involving people alleged to be affiliated with Al Qaeda. Since the systems Mr. Klein referred to are Internet-based, the monitoring he described does not appear to be connected to another alleged NSA program to collect information on domestic phone calls.

USA Today reported the existence of that program earlier this week, but the White House has refused to confirm it and some companies the newspaper said were involved have disputed the report.

The 90-minute court hearing yesterday was devoted primarily to the question of whether the documents Mr. Klein gave to the foundation should be returned to the company, made public, or treated confidentially as the case proceeds.

At the outset of yesterday’s session, an attorney for AT&T, David Anderson, asked Judge Walker to close the courtroom yesterday to protect the company’s purported secrets, but the judge declined. Mr.Anderson argued that the Electronic Frontier Foundation should be required to return the AT&T documents to the company.

“Trade secret rights rise to the level of property rights,” the lawyer said.”It’s not the finders keepers, losers weepers rule that applies to this case. It is the rule of law that applies to this case.”

An attorney for the foundation, Maria Morris, told the judge that the group considers the documents to be evidence of a crime.

“They are asking this court to suppress evidence of AT&T’s criminal activity,” she said.

Mr. Anderson called that allegation “reckless at best” and described AT&T as “one of the great companies of the United States.”

Judge Walker agreed to order the foundation and its attorneys not to distribute the documents AT&T asserts contain trade secrets,but he said he did not have authority to impose a similar order on Mr. Klein, who has cooperated with the foundation but is not a party to the suit. The judge noted that AT&T could take legal action if its former employee breached a confidentiality agreement. “You have remedies against Mr. Klein,” he said.

However, such an attempt could be futile, as it also emerged at the hearing that Mr. Klein has already provided copies of the documents to the New York Times. The newspaper has reported on Mr. Klein’s allegations, but has not made the AT&T documents public.

After Ms. Morris pressed repeatedly to make public those documents and other papers filed with the court, Judge Walker chided her. “Be a little less concerned with getting this out to the public than with getting this to the court,” he said. “You are not running a public relations operation.”

The Justice Department has moved to have the case thrown out of court because it implicates state secrets, but that issue was discussed only briefly at yesterday’s hearing. An attorney for the government, Carl Nichols, urged Judge Walker to examine classified affidavits in which top intelligence officials say litigating the case could expose details of anti-terrorism surveillance efforts.

While Judge Walker set formal arguments on the issue for next month, he expressed some skepticism yesterday about the government’s effort to dismiss the suit. “What you have in essence is a common law privilege, while what the plaintiffs are asserting are constitutional claims,” he said. “How am I going to be able to weigh those?”

The judge, who was appointed by President George H.W. Bush, also asked how the plaintiffs would be able to address national security assertions to which they are not privy.

“They won’t be. Unfortunately or fortunately, that is the way it is done and that is the way it has to be done,” Mr. Nichols said.

To defend itself, AT&T has also retained one of America’s most prominent conservative attorneys, Bradford Berenson. He served as an associate counsel to President Bush and is now in private practice in Washington.

Mr. Berenson told Judge Walker yesterday that critics of the NSA’s programs should be suing the government, not AT&T. “AT&T is essentially an innocent bystander caught in the crossfire,” he said.

AT&T has declined to say what involvement, if any, it has in NSA surveillance efforts, but in a statement yesterday acknowledged that its assistance may go beyond what is mandated by law. “It would be as irresponsible for AT&T to refuse to assist in protecting the country when the law allows or requires it as it would be for AT&T to provide such assistance when the law forbids it,” a spokesman, Marc Bien, said.

“AT&T has not been forthright with its customers or the American people about what it is doing,” Mr. Brosnahan told reporters. He said Mr. Klein would like to testify at upcoming Senate hearings on the reported surveillance programs.