A former White House computer expert says the e-mail system used by President Bush's top aides is a "primitive" setup that creates a "high" risk of losing data.

In written statements submitted to a House committee Tuesday, Steven McDevitt cites a study by the White House technical staff that found an estimated 1,000 days on which e-mail was missing.

Federal law requires electronic messages to be preserved.

Rep. Henry Waxman, D-Calif., chairman of the House Oversight and Reform Committee, accused the White House on Tuesday of delaying retrieval of e-mails until Bush leaves office in January 2008.

White House administrative officer Theresa Payton defended the Bush administration's handling of its electronic messages and the effort to retrieve any missing data.