A federal judge yesterday held reporters from four major news organizations in contempt for refusing to name confidential sources in their reports on a nuclear scientist once accused of being a spy.

U.S. District Judge Thomas Penfield Jackson said that reporters for the Associated Press, the Cable News Network, the Los Angeles Times and the New York Times must tell attorneys for Wen Ho Lee the names of federal officials who gave them confidential information about the former nuclear-weapons scientist. The judge fined the news organizations $500 a day each until they provide the names, but said payments can be delayed pending appeals.

A reporter for The Washington Post might become subject to the order once he is deposed in Lee's pending civil lawsuit, which accuses federal officials of illegally leaking confidential information that harmed his reputation.

It was the second time in two weeks that a federal judge in Washington has held a reporter in contempt for refusing to name confidential sources. In the other case, U.S. District Chief Judge Thomas F. Hogan held Time magazine reporter Matthew Cooper in contempt for refusing to testify before a federal grand jury investigating the leak of a CIA officer's identity.

Unlike that case, the possibility of jail time is not at issue in Lee's lawsuit. Attorneys for the various news organizations vowed to file immediate appeals.

"It's becoming a perilous time for journalists who rely on information provided under terms of confidentiality," said Floyd Abrams, the attorney for reporters James Risen and Jeff Gerth of the New York Times. "The upcoming rulings by the Court of Appeals in Washington will send an important message about journalists being able to do their jobs, particularly about reporting on the functioning of government."

The cases were the first of their kind to be adjudicated in Washington since 1981. Lee's case pitted the rights of the media against the scientist's right to pursue evidence that could prove his claims. Depositions by Lee's attorneys of government officials yielded no useful information, said Jackson, who has deemed the journalists' accounts to be central to proving Lee's claims of Privacy Act violations.

Lee contends that officials from the Justice Department, FBI and Energy Department leaked private information about him and his family when he was under investigation for allegedly spying for China while employed at the Los Alamos Nuclear Laboratory in New Mexico. Several news organizations named Lee as the chief suspect.

He was charged in December 1999 with 59 counts of mishandling classified information and violating the Atomic Energy Act, and jailed for nine months pending trial. But the FBI later acknowledged the probe had been flawed, and allegations of spying collapsed. Lee pleaded guilty in September 2000 to a single felony charge of downloading nuclear weapons data to portable tapes and was freed.

Lee's attorneys turned to Jackson last year when they decided to seek the reporters' depositions. In a ruling in October, Jackson ordered that the journalists must appear for depositions and "truthfully answer questions as to the identity of any officer or agent of defendants . . . who provided information to them directly about Wen Ho Lee."

Although the journalists showed up for depositions, they refused to name their sources. They invoked First Amendment defenses that have been upheld by the courts that allow journalists not to identify confidential sources. That led to a hearing before Jackson yesterday, in which he heard arguments on the contempt matter.

Since Jackson already had rejected the media's First Amendment arguments, the outcome of yesterday's 90-minute hearing was a foregone conclusion. "We knew this would be the ruling, but we are pleased Judge Jackson understands this is a matter of principle, not an affront to the court," said Charles D. Tobin, attorney for former CNN reporter Pierre Thomas, who now is with ABC.

Lee's attorneys had suggested the judge impose daily fines of $1,000 per reporter; attorneys for the news organizations argued against a contempt finding and said that if fines were imposed, they should be minimal, perhaps $1 a day. In his ruling, Jackson said that $1,000 seemed too punitive and that $1 seemed "insufficient to ever coerce compliance." So he said he was "splitting the difference" with the $500-a-day penalties.

The other journalists in the case are Associated Press reporter H. Josef Hebert and Robert Drogin of the Los Angeles Times. The Post reporter is Walter Pincus.