The group asked the judge on Thursday to demand an explanation regarding alleged inconsistencies between testimony at a congressional hearing last week and what the White House told a federal court in January.

"This evidence demonstrates defendants' blatant disregard for the truth and the processes of this court," Citizens for Responsibility and Ethics in Washington told U.S. District Judge Henry Kennedy in court papers.

CREW wants the judge to compel the Executive Office of the President to explain why it should not be held in contempt of court.

In a sworn declaration, White House official Theresa Payton told the court on Jan. 16 that "substantially all" e-mails from 2003 to 2005 should be contained on back-up computer tapes.

However, at a hearing of the House Oversight and Government Reform Committee on Feb. 26, the panel's Democrats released a White House document that called that claim into question.

E-mail was missing from a White House archive for the period of Sept. 30-Oct. 6, 2003 from the office of Vice President Dick Cheney, the White House document states. The backup tape covering that seven-day period was not created until Oct. 21, 2003, raising the possibility that e-mail was missing from the earlier period. That time span was in the earliest days of the Justice Department's probe into whether anyone at the White House leaked the CIA identity of Valerie Plame. Cheney's chief of staff, I. Lewis "Scooter" Libby, was eventually convicted by a jury of four felonies in the leak probe.

The congressional panel also released written statements by a former White House technical supervisor saying that a 15-person team conducted an extensive multi-phase assessment that resulted in a final 250-page analysis on the problem of missing White House e-mail.

In her sworn declaration to the federal court in January, the White House official said she was aware of a chart created by a former employee regarding missing e-mails, but said nothing about the 250-page analysis.