A federal judge agreed Monday to allow a private group to delve into the operations of an office at the White House as part of a controversy over whether large amounts of e-mail have disappeared.

Permitting any private organization to inquire into White House functions is an unusual step, a point U.S. District Judge Colleen Kollar-Kotelly underscored in her six-page order.

The judge said she will allow Citizens for Responsibility and Ethics in Washington to gather a "very limited" amount of information from the White House Office of Administration, which is in charge of preserving e-mail.

The issue for Kollar-Kotelly is whether the Office of Administration operates with substantial independent authority. If the judge finds that it does, the private group can pursue data about what went wrong with the White House e-mail system.

If the judge decides that the office's functions are limited to serving the president, she likely will dismiss the suit.

Kollar-Kotelly rejected a proposal by the Office of Administration to provide a written description of its functions, saying CREW should be allowed to conduct evidence-gathering over the next 45 days.

The White House is required to retain electronic messages under the President Records Act and the Federal Records Act.

The citizens group says more than 10 million e-mails were not properly retained and recently called for a criminal investigation. The White House says there is no evidence that e-mail is missing.

CREW sued the Office of Administration last year under the Freedom of Information Act, seeking records about White House e-mail problems. The White House says the Office of Administration is not subject to the public records law and that CREW's lawsuit should be dismissed.

The Office of Administration, along with the Office of Management and Budget and other White House units with substantial independent authority, regularly provided records under the Freedom of Information Act in the past.

The White House's e-mail problems were first publicly disclosed more than two years ago by the special prosecutor in the CIA leak probe.