WASHINGTON — Opening a new front in the Bush administration’s battle to keep its records confidential, the Justice Department is contending that the White House Office of Administration is not subject to the Freedom of Information Act.

The department’s argument is in response to a lawsuit trying to force the office to disclose what it knows about the disappearance of White House e-mails.

The Office of Administration provides administrative services, including information technology support, to the Executive Office of the President. Most of the White House is not subject to the FOIA, but certain components within it handle FOIA requests. Last year, the Office of Administration processed 65 FOIA requests.

However, the Justice Department maintained in court papers filed Tuesday that the Office of Administration has no substantial authority independent of President Bush and therefore is not subject to the FOIA’s disclosure requirements.

Regarding the Bush administration’s conduct, “this behavior is perfectly consistent with the way they have handled freedom of information issues over the past six years,” said Lucy Dalglish, executive director of the Reporters Committee for Freedom of the Press. “When they don’t want to comply with the law, they just shamelessly argue they are not subject to the law. It’s arrogant and disrespectful to citizens.”

In its filing in U.S. District Court, the Justice Department said, “to be sure, OA currently has regulations implementing FOIA and has not taken the position” previously that it is exempt from the Freedom Of Information Act. To justify a change, the court papers rely on a court ruling in the 1990s that the National Security Council was not subject to FOIA. Previously, the NSC had handled FOIA requests.

The office of administration has prepared estimates that there are at least 5 million missing White House e-mails between March 2003 and October 2005, according to the lawsuit filed by Citizens for Responsibility and Ethics in Washington, a private advocacy group. The White House has said it is aware that some e-mails may not have been automatically archived on a computer server for the Executive Office of the President. The e-mails, the White House has said, may be saved on backup tapes.

“The Office of Administration is looking into whether there are e- mails not automatically archived; and once we determine whether or not there is a problem, we’ll take the necessary steps to address it,” White House spokesman Scott Stanzel said.

The first indication of a problem came in early 2006 when special counsel Patrick Fitzgerald raised the possibility that records sought in the CIA leak investigation involving the outing of Valerie Plame could be missing because of an email archiving problem at the White House.

The issue came into focus early this year amid the uproar over the firing of U.S. attorneys. It turned out that aides to Mr. Bush improperly used Republican Party-sponsored e-mail accounts for official business and that an undetermined number of e-mails had been lost in the process.

The Justice Department Web site, which lists all FOIA contacts inside the government, identifies seven units inside the Executive Office of the President as responding to FOIA requests, including the Office of Administration.

The Office of Administration “has certainly acted like an agency in the past,” said Meredith Fuchs, general counsel to the National Security Archive, a private group advocating public disclosure of government secrets.

Ms. Fuchs’s organization filed a request in February 2006 after Mr. Fitzgerald disclosed that emails might be missing. When the Office of Administration finally denied the private group’s request in June of this year, the office said it was not an “agency” as defined by the Freedom of Information Act and was therefore not subject to the law’s requirements.

The administration has been resisting disclosure of information on an array of fronts.

In September 2006, Vice President Cheney’s lawyer instructed the Secret Service that it “shall not retain any copy” of material identifying visitors to the vice president’s official residence. The lawyer, Shannen Coffin, wrote the letter as the Washington Post sought copies of Mr. Cheney’s visitors.

The letter regarding the vice president’s residence was in addition to an agreement quietly signed between the White House and the Secret Service when questions were raised about visits to the executive compound by convicted influence peddler Jack Abramoff.

That agreement, which didn’t surface publicly until late last year, said White House entry and exit logs were presidential records not subject to disclosure under the Freedom of Information Act.

When the agreement was signed in May 2006, a number of private groups and news organizations had filed FOIA requests with the Secret Service in an effort to identify how many times Abramoff or members of his lobbying team visited the White House.