WASHINGTON - Five Transportation Security Administration employees have been placed on administrative leave in connection with the posting on the Internet of sensitive guidelines about airport-passenger screening.

The move was disclosed as a Senate panel questioned administration officials yesterday about the second embarrassing security flap at the Homeland Security Department in as many weeks. The Secret Service, also part of the sprawling department, is investigating how a couple of would-be reality-TV stars were able to get into a White House state dinner without an invitation.

Assistant Homeland Security secretary David Heyman told the panel that a full investigation into the Internet security lapse was under way and that the TSA employees have been taken off duty pending the results of that probe.

The Homeland Security Department has also stopped posting documents with security information on the Internet until the TSA review is complete, Heyman told the Senate Homeland Security and Governmental Affairs committee.

The passenger-screening document was improperly on the Internet in a way that could offer insight into how to sidestep security.

"Even what appeared to be an innocent posting to help federal contractors can have serious consequences for our security," said Sen. Susan Collins, R-Maine.

Heyman said he did not know who at TSA signed off on the document going on the Web. The TSA removed the document from the Internet on Sunday after the lapse was reported on a blog.

Among many sensitive sections, the document outlines who is exempt from certain additional screening measures, including members of the U.S. armed forces, governors and lieutenant governors, the mayor of Washington, D.C., and their immediate families.

It also offers examples of identification documents that screeners accept. And it explains that diplomatic pouches and certain foreign dignitaries with law-enforcement escorts are not subjected to any screening at all. It said certain methods of verifying identification documents aren't used on all travelers during peak travel crushes.

TSA said the document is now outdated. It was posted in March by TSA on the Federal Business Opportunity site. The posting was improper because sensitive information was not properly protected, TSA spokeswoman Kristin Lee said.

As a result, some Web sites, using widely available software, were able to uncover the original text of sections that had been blacked out for security reasons.

Although the TSA removed the document from the Federal Business Opportunity site on Sunday, copies - with the redacted portions exposed - circulated on the Internet and remain posted on other Web sites not controlled by the government.

Noting that the transportation agency uses multiple layers of security, Lee said, "TSA is confident that screening procedures currently in place remain strong."

The document also describes these screening protocols:

_ Individuals with a passport from Cuba, Iran, North Korea, Libya, Syria, Sudan, Afghanistan, Lebanon, Somalia, Iraq, Yemen, or Algeria should be given additional screening unless there are specific instructions not to.

_ Aircraft flight-crew members in uniform with valid IDs are not subject to restrictions on liquid, gel, aerosol and footwear.

Former TSA Administrator Kip Hawley said that the document was not something a security agency would want to inadvertently post online but that it's not a road map for terrorists.

"Hyperventilating that this is a breach of security that's going to endanger the public is flat wrong," Hawley said.