Dozens more White House officials used e-mail accounts set up by the Republican National Committee than the Bush administration has previously acknowledged, a House investigative panel said.

At least 88 White House officials, including senior political adviser Karl Rove, a former chief of staff, Andrew Card, and a former political director, Ken Mehlman, used the accounts extensively, according to a report by the House oversight panel. The White House had earlier acknowledged the use of 50 such accounts.

The e-mail accounts were used for official purposes, such as communicating with federal agencies, and by law should have been preserved, the report said. The committee has been investigating the disappearance of administration e-mails and whether White House officials used outside e-mail accounts to avoid requirements of public-records disclosure laws.

“This should be a matter of grave concern for anyone who values open government and the preservation of an accurate historical record of the decision-making process inside the White House,” said Rep. Henry Waxman, a California Democrat who heads the committee.

There is “the possibility of a violation of the Presidential Records Act,” Mr. Waxman said.

The RNC has begun trying to preserve the e-mails, and that effort has demonstrated that the system was used extensively, Mr. Waxman’s report said. The RNC found 140,216 e-mails sent or received by Mr. Rove, about half of those sent to or from officials with government e-mail addresses.

Bush administration spokesman Tony Snow said Mr. Waxman’s report was being reviewed by White House Counsel Fred Fielding and there would be no direct comment until that was done.

“This is an administration that’s been very careful about following the law,” Mr. Snow said. “We take it seriously.”

Senator Leahy, the chairman of the Senate Judiciary Committee looking into the White House’s role in the political firings of U.S. prosecutors, said he has been told the White House has recovered many of Mr. Rove’s e-mails previously believed lost.

“Now that we know more than 100,000 of Mr. Rove’s secret emails have not been destroyed, I hope the White House will respond to my request for any emails from his account that are relevant to the Judiciary Committee’s investigation,” Mr. Leahy, a Democrat of Vermont, said in a statement.

The Office of Special Counsel, an independent agency that enforces the Hatch Act ban on mixing government and political business, said in April that it will investigate whether White House aides improperly used the Republican Party e-mail system for government business.

Mr. Snow said the accounts were set up “on a model based on the prior administration in an effort to avoid Hatch Act violations.”

Mr. Waxman’s committee said many of the White House e-mails on RNC accounts weren’t retained before the third quarter of 2006 as required under the Presidential Records Act of 1978.

White House spokesman Scott Stanzel told reporters on April 11 that a handful of officials used RNC e-mail accounts. A later estimate from White House spokeswoman Dana Perino put the number at 50 officials with RNC e-mail accounts.

The RNC and the White House preserved no e-mail records for Mr. Mehlman, the chairman of the RNC during Bush’s 2004 re-election campaign.

“This is no accident,” said Anne Weisman, chief counsel of Citizens for Responsibility and Ethics in Washington, a nonprofit watchdog group. “They were aware of the fact that if they used their official e-mails, they would be preserved. So they exploited this alternative communication method.”

Mr. Waxman’s report suggested Attorney General Gonzales failed to try to preserve the e-mails as required when he was White House counsel.

Mr. Waxman said he intends to investigate further what role Mr. Gonzales played. “We want to investigate what then White House Counsel Alberto Gonzales knew about the use of RNC e-mails,” he said.

“There is evidence that Mr. Gonzales or counsels working in his office knew in 2001 that Karl Rove was using his RNC e-mail account to communicate about official business, but took no action to preserve Mr. Rove’s official communication,” the committee report said.

Mr. Waxman has requested email records of 25 federal agencies that may have received e-mails from White House officials using RNC or Bush-Cheney ’04 accounts.

The committee is considering issuing subpoenas to Bush-Cheney ’04 campaign officials to force them to identify which White House officials also had campaign e-mail accounts in addition to the RNC accounts, the committee report said.

“Our concern is whether there was compliance with the Presidential Records Act,” said Karen Lightfoot, a spokeswoman for Waxman.