Five journalists in the US have been fined for refusing to identify sources behind stories on nuclear espionage.
Wen Ho Lee says he was targeted by official leaks
A judge said nuclear scientist Wen Ho Lee, who was cleared after being held in jail on spying charges, needed the names as he was suing the government.
He found the five in contempt of court and ordered them to pay $500 (£275) a day until they named their sources.
The reporters say confidentiality is critical for giving the public information on important issues.
The five journalists are: Associated Press reporter H
Josef Hebert, James Risen and Jeff Gerth of The New York Times, Robert Drogin of the Los Angeles Times, and Pierre Thomas of ABC.
The men said they would appeal, and the judge agreed to suspend the fines until the appeal was heard.
The journalists reported on the case of Taiwanese-born weapons designer Wen Ho Lee, who worked at Los Alamos National Laboratory in New Mexico and was held in solitary confinement on accusations that he had spied for China.
Los Alamos is the US' main nuclear research facility
Mr Lee denied the charges. He was released after a plea bargain in which he pleaded guilty to one of the 59 charges against him - mishandling sensitive materials.
He is seeking the identity of the journalists' sources for a lawsuit against the US government, which alleges that officials gave false information about him to the media in order to damage his reputation.
The reporters say they have provided as much information as they could without breaking a commitment to
protect their sources.
Hebert, who has worked at the AP agency for 34 years, defended himself and his colleagues.
"I believe strongly that when a reporter gives a source
the assurance that his or her confidentiality will be
protected, he cannot go back on his word," he said.
"To do so would be a disservice to the source, destroy the
reporter's credibility with future sources and hinder
It is the second time this month that a US federal judge has ruled against journalists refusing to discloses sources.
On 9 August a Time Magazine reporter was held in contempt over an investigation into the exposure of an undercover CIA agent.
Lucy Dalglish of the Reporters Committee for the Freedom of the Press said the latest ruling was a threat to free speech, as guaranteed by the First Amendment of the US constitution.
"All this has to do with secrecy. The government is
trying to keep more and more secrets all the time, and
journalists are working harder to uncover those secrets.
Given the terrorism climate, all this has come to a head,"
Mr Lee's lawyer said it was not about the First Amendment, and that the reporters were withholding vital information.