WASHINGTON – A federal appeals court yesterday upheld a ruling against two reporters who could go to jail for refusing to divulge their sources to investigators probing the leak of an undercover CIA officer’s name to the press.

The three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit sided with prosecutors in their attempt to compel Time magazine’s Matthew Cooper and the New York Times’ Judith Miller to testify before a federal grand jury about their confidential sources.

“We agree with the District Court that there is no First Amendment privilege protecting the information sought,” Judge David Sentelle said in the ruling, which was unanimous.

Floyd Abrams, the lawyer for both reporters, said he would ask the full appeals court to reverse yesterday’s ruling. “Today’s decision strikes a heavy blow against the public’s right to be informed about its government,” Mr. Abrams said in a statement.

In October, Judge Thomas Hogan held the reporters in contempt, rejecting their argument that the First Amendment shielded them from revealing their sources. Both reporters face up to 18 months in jail if they continue to refuse to cooperate.

The special prosecutor in the case, Chicago U.S. Attorney Patrick Fitzgerald, is investigating whether a crime was committed when someone leaked the identity of CIA officer Valerie Plame. Her name was published in a 2003 column by Robert Novak, who cited two senior Bush administration officials as his sources.

The column appeared after Ms. Plame’s husband, former Ambassador Joseph Wilson, wrote a newspaper opinion piece criticizing President Bush’s claim that Iraq had sought uranium in Niger. The CIA had asked Mr. Wilson to check out the uranium claim. Mr. Wilson has said he believes his wife’s name was leaked as retaliation for his critical comments.

Disclosure of an undercover intelligence officer’s identity can be a federal crime if prosecutors can show the leak was intentional and the person who released that information knew of the officer’s secret status.

Mr. Fitzgerald said he wants to bring his 14-month-old investigation “to a prompt conclusion.” The judges agreed that “the government has shown critical need for the reporters to comply with the subpoenas in this case,” he said in a statement.

Both Time and the New York Times said they would not give up their fight. The Times’ publisher Arthur Sulzberger Jr. said the newspaper also would press for “a federal shield law” to make it harder to subpoena reporters or compel their testimony. Legislation has been introduced in Congress.

White House press secretary Scott McClellan had little to say about the appeals court ruling. “The president has made it clear that he wants to get to the bottom of this matter,” Mr. Mc-Clellan said, adding that President Bush also has urged anyone with information on the case to come forward.

Mr. Cooper is a White House correspondent for Time who has reported on the Plame controversy. He agreed in August to provide limited testimony about a conversation he had with Lewis “Scooter” Libby, Vice President Cheney’s chief of staff, after Mr. Libby released Mr. Cooper from his promise of confidentiality.

Mr. Fitzgerald then issued a second, broader subpoena seeking the names of other sources.

Ms. Miller is facing jail for a story she never wrote. She had gathered material for an article about Ms. Plame, but ended up not doing a story.