WASHINGTON — An ethics advocacy group asked the FBI on Wednesday to investigate the White House e-mail controversy, saying electronic messages about the Valerie Plame affair may have been destroyed.

Citizens for Responsibility and Ethics in Washington is basing its request on a White House document describing an effort to recover a week's worth of missing e-mail in 2003 from the office of Vice President Dick Cheney.

The missing e-mail was from a week around the time the Justice Department had begun a criminal investigation into who in the Bush administration leaked Plame's CIA identity to reporters.

White House technicians eventually retrieved e-mail from the missing week, but it is unclear whether all the e-mail from Cheney's office that week has been found.

Cheney's former chief of staff, I. Lewis "Scooter" Libby, was convicted of perjury, obstruction and lying to the FBI in the Plame inquiry.

An investigation is warranted because of the unexplained disappearance of an entire week's worth of e-mails from Cheney's office while the Justice Department was investigating top White House officials, according to CREW.

The request was outlined in a letter from the group to FBI Director Robert Mueller.

The White House document that CREW relies on was placed on the public record at a Feb. 26 congressional hearing.

It spells out how White House computer experts had to go to a computer backup tape to hunt for missing e-mail from Sept. 30-Oct. 6, 2003 from Cheney's office. The backup tape the White House used was created on Oct. 21, 2003, two to three weeks after the e-mail that technicians were trying to find.

The starting date for the missing e-mail, Sept. 30, 2003, was the day the White House counsel's office sent two notices to employees ordering the preservation of all material relevant to the Plame investigation.

No e-mail for the missing week could be found in locations on the backup tape where it could be expected to turn up. Technicians had to recover e-mail from individual accounts stored on the backup tape.

A backup computer tape is a picture of how things look when the tape is created, raising the possibility that an e-mail deleted before the tape is created will not show up.

The FBI referred questions about CREW's request to the Justice Department, where a spokesman said it is being reviewed. On Feb. 4, CREW asked the department to appoint a special prosecutor to investigate whether the White House violated federal record-keeping laws by knowingly failing to preserve its e-mail. In response, Deputy Assistant Attorney General John Keeney advised CREW to bring any information it had to the FBI's attention.

CREW is suing the Executive Office of the President over the White House e-mail issue and was to question the head of the Office of Administration about it on Thursday. White House spokesman Scott Stanzel declined to comment, citing the continuing lawsuit.

Also Wednesday, a second private group suing the Executive Office of the President said in a court filing that the White House misled a federal magistrate in January by not revealing the problem of missing e-mail from Cheney's office.

In a sworn statement Jan. 15 responding to questions from U.S. Magistrate Judge John Facciola, White House official Theresa Payton said that "this office does not know if any e-mails were not properly preserved in the archiving process."

Details of the e-mail problem involving Cheney's office didn't come to light until the Feb. 26 congressional hearing.

In its latest court filing Wednesday, the National Security Archive asked the federal court to authorize questioning of Payton about her January declaration, which also stated that computer backup tapes "should contain substantially all the e-mails."