WASHINGTON -- Government inspectors said in a report Wednesday that they discovered more e-mails that raise questions about work performed at Yucca Mountain, including one message that suggested backdating notebooks and another with a recommendation to "make up something."

The report prepared by the Energy Department inspector general refocused attention on Yucca Mountain quality assurance, an area in which department has been regularly criticized.

DOE spokesman Craig Stevens said the department was aware of the e-mails, which he characterized as a "blip in the cosmos of Yucca Mountain." Critics said the audit provides fresh evidence of the proposed nuclear waste dump's management shortcomings.

"This report reinforces the complete lack of confidence I have in the ability of the DOE to honestly evaluate the safety of Yucca Mountain and to truly enforce any type of quality assurance program," said Rep. Jim Gibbons, R-Nev.

In March, the Yucca program was tossed into turmoil with the release of a cache of e-mail messages in which U.S. Geological Survey hydrologists discussed possible falsification of quality assurance documents on water infiltration research.

The 16-page report issued Wednesday was part of an ongoing criminal investigation related to those messages, which also are the topic of a probe by a U.S. House subcommittee. Auditors said they reviewed e-mail written by or associated with workers being investigated.

Auditors said the latest review "identified a number of e-mails containing language that could indicate possible conditions adverse to quality."

Investigators did not say how many questionable messages were found or whether they referred to the same matters uncovered in March. Five e-mails were excerpted in the report.

In one excerpt, an author referred to a report that concerned rainfall. "Our best guess. Screw 'em. It's a lovely, 85, sunny, warm breeze. It's nice to be disconnected and not caring whether it's QA (quality assurance) or not. If you can't give them QA, that's fine."

Another said "... we may want to backdate the notebook to when we started putting things together."

Quality assurance requires scientists and engineers to record and document their research, computer modeling and field reports meticulously so that they can be verified and confirmed as part of repository safety licensing.

The e-mails disclosed in March and the latest messages disclosed by auditor indicated that some workers held the quality assurance process in low regard.

Additionally, auditors said that the Office of Civilian Radioactive Waste Management in DOE fell short in how it reviewed internal messages to ensure that possible quality control problems were being identified and investigated.

Out of 10 million e-mails that accumulated over years, the Energy Department deemed nine million irrelevant for repository licensing. But inspectors said they found e-mails among the rejects that should have raised flags.

DOE spokesman Stevens said the department is responding by preparing a new review of the 10 million e-mails, plus another 4 million, using statistical sampling to examine a more comprehensive set of messages than before.

Paul Golan, acting director of the Yucca Mountain project, has issued a corrective action plan that will guide the reviews, and people who are examining e-mails for hints of problems are being retrained, Stevens said.

Stevens said DOE examiners found some of the new e-mails this summer while others were brought to the department's attention by the inspector general and are being examined.

"The issue of the e-mails is something that has been looked at ad nauseam by people in this department," Stevens said.

"When this came to the knowledge of the front office, they worked quickly to get on top of this.

"In the universe of the Yucca Mountain Project, this report isn't even a twinkle from the most distant star," Stevens said.

The audit prompted some members of Nevada's congressional delegation to renew calls for an independent investigation of the nuclear waste project.

"What is clear from this report is that allowing the DOE to review its own quality assurance records is like giving prisoners the keys to their own jail cells," said Rep. Shelley Berkley, D-Nev.

Rep. Jon Porter, R-Nev., who leads the House subcommittee that has been conducting an examination of the e-mails and related issues, said the audit "highlights what I think is a culture of mismanagement at DOE. They left out nine million e-mails, and that troubles me."

Energy Department officials were not certain how long it would take to perform the new examination. The department plans to spend more than a year and more than $1 million to try to put to rest questions about Yucca Mountain science that were raised by the e-mails disclosed in March.

Some officials have cautioned against reading much into e-mails offered without background or context.

Joseph Hevesi, a USGS hydrologist identified as one of the e-mail authors, told Porter's subcommittee at a hearing in June that provocative messages he wrote were merely "water cooler talk." Hevesi said he did not falsify documents on the project.