In an unexpected announcement, the Energy Department said it will decrease the number of polygraphs administered to employees with access to "nuclear secrets," particularly in the nation's weapons laboratories.

The deputy energy secretary, Kyle E. McSlarrow, said at a Senate hearing that the new policy was likely to reduce the number of people given polygraph tests to 4,500, mainly in sensitive arms and intelligence posts, from some 20,000 now.

McSlarrow said there has been increasing criticism of the techniques used in polygraphs and the department agreed with some of the critics. The increase in use was a result of the Wen Ho Lee case.

In 2001, Congress instructed the Department of Energy to adopt widespread polygraph screening in reaction to the case of Wen Ho Lee, the scientist at the Los Alamos weapons laboratory in New Mexico who was suspected of being a spy but was freed from jail in September 2000 after admitting to a security violation. That order raised an outcry from experts who ridiculed lie detector tests as pseudoscientific and a potential threat to national security.

Last October, in a report requested and paid for by the Energy Department, a panel convened by an arm of the National Academy of Sciences said polygraph testing was too flawed to use for security screening. The panel said lie detector tests did a poor job of identifying national security risks and were likely to produce accusations against innocent people.

The Senate panel conducting the hearing was chaired by Sen. Pete Domenici (R-NM) who added:

"This is a smart decision. I have been appalled by the D.O.E.'s continued massive use of polygraph tests in the wake of a national study condemning the reliability of these tests. Our national scientists deserve better."