The Energy Department, in response to a security scandal at the Los Alamos weapons lab, ordered a halt yesterday to classified work at as many as two dozen facilities that use removable computer disks like those missing at the New Mexico lab.

Energy Secretary Spencer Abraham said the "stand-down" at operations using the disks, containing classified material involving nuclear weapons research, is needed to get better control over the devices.

The disks, known as "controlled removable electronic media," or CREM, have been at the heart of an uproar over lax security at the Los Alamos National Laboratory, where work has been stopped as scientists search for two of the disks reported missing on July 7.

Nineteen workers have been suspended pending the outcome of an investigation into the missing data devices and an incident in which an intern was injured recently in a laser accident.

The missing Los Alamos disks raised concern at the Energy Department about the handling of the devices at other facilities involved in nuclear weapons research, department officials said.

Abraham said he wants to "minimize the risk of human error or malfeasance" that could compromise the classified nuclear-related information held in the devices, which are used at Energy Department facilities nationwide in nuclear-related work.

"While we have no evidence that the problems currently being investigated are present elsewhere, we have a responsibility to take all necessary action to prevent such problems from occurring at all," Abraham said in a statement.

The stand-down involves classified work across the government's nuclear weapons complex wherever the CREM storage devices are used, the official said. It will continue until an inventory of the devices is completed and new control measures on their use is put in place, said Energy Department spokesman Joe Davis. Employees using the disks must also undergo security training.

Among the facilities that are preparing for an interruption of classified work are the Argonne National Laboratory outside Chicago; the nuclear weapons plant in Oak Ridge, Tenn.; and the Sandia National Laboratories in Albuquerque, where a missing classified disk was reported found last week.