A federal appeals court has ruled that the names of Connecticut librarians who had been asked to help in an FBI terrorism investigation under the Patriot Act (search) will remain secret pending arguments from prosecutors.

The American Civil Liberties Union is seeking the identity of the librarians who received an FBI demand for records about library patrons.

On Tuesday, the U.S. 2nd Circuit Court of Appeals in New York put on hold a lower court's decision that had lifted a gag order shielding the identity of librarians.

U.S. District Court Judge Janet Hall (search) in New Haven had ruled earlier this month in favor of the ACLU, which argued that the gag order prevented its client from participating in a debate over whether Congress should reauthorize the Patriot Act.

Prosecutors said the gag order prevented only the release of the client's identity, not the client's ability to speak about the Patriot Act.

Prosecutors also argued that revealing the identity of the librarians would be "an alarm bell" that could tip off suspects and jeopardize a federal investigation into terrorism.

Hall rejected many of the same FBI arguments in her ruling to lift the gag order.

"The government may intend the nondisclosure provision to serve some purpose other than the suppression of speech," Hall wrote. "Nevertheless, it has the practical effect of silencing individuals with a constitutionally protected interest in speech and whose voices are particularly important in an ongoing national debate about the intrusion of governmental authority into individual lives."

The Patriot Act, passed shortly after the Sept. 11 attacks, removed the requirement that the records sought be those of someone under suspicion. Now, anyone's records can be obtained if the FBI considers them relevant to a terrorism or spying investigation.