U.S. District Judge Gladys Kessler issued a stay of an earlier order to give government lawyers more time to appeal.
Kessler said the stay will remain in effect until a federal appeals court has ruled in the matter, according to federal law clerk Shina Majeed. That ruling could be months away.
On Aug. 2, Kessler gave the Justice Department 15 days to release the names, ruling at the time that federal attorneys had not proven the need for a blanket policy of secrecy for more than 1,000 people picked up since the attacks.
The government informed the court of its intention to appeal last week, arguing in documents that Kessler had missed the point about keeping the names secret.
Kessler largely limited her original ruling to the government's obligations under the federal Freedom of Information Act. In a partial victory for the Justice Department, she at that time rejected the notion that the civil liberties groups have a constitutional free-speech right to some information.
Kessler also agreed with the government that it may keep other details secret, ruling there are valid security reasons for not revealing the dates and location of arrests and detentions.
The Justice Department said that if Kessler's ruling is allowed to stand, the investigation of the terrorist attacks would be harmed.
The ruling "impedes one of the most important federal law enforcement investigations in history, harms our efforts to bring to justice those responsible for the heinous attacks of Sept. 11, and increases the risk of future terrorist threats to our nation," Robert McCallum, assistant attorney general for civil rights, said on Aug. 2, after Kessler ordered the release of the names.
In her opinion earlier this month, Kessler refuted the government's case that the terrorist group al Qaeda would be tipped to how much progress investigators had made if the detainees names were released. She said al Qaeda would already be aware if operatives in the United States were missing.
In granting the stay, she offered no estimation of the government's chance of success in appealing her ruling.
"Given fact that stays are routinely granted in Freedom of Information cases, the disclosure of the detainees names would moot any appeal and the government had promised to seek an expedited appeal," Kessler said in her ruling.
Her previous order gave the government 15 days to comply and allowed only two exceptions: if the detainee is a material witness to a terror investigation and if the person being held does not want to be identified.
In her earlier opinion, Kessler wrote that in the government affidavits "nowhere declare that some or all of the detainees have connections to terrorism. Nor do they provide facts that would permit the court to infer links to terrorism. For example, the government has provided no information on the standard used to arrest and detain individuals initially."
The government disclosed in June that at least 147 people still were being held, including 74 on charges involving immigration infractions. Prosecutors have not said how many are being held as material witnesses.
The government also disclosed that between Sept. 11 and June 24, there were 752 arrested or detained in immigration charges. The others were arrested for differing charges.