The US. Department of Energy, which runs the nation's nuclear arms research, ordered the widespread suspension of classified operations last night as part of a security crackdown sparked by lapses at the Los Alamos laboratory.
A statement by Energy Secretary Mr Spencer Abraham said the situation at the Los Alamos National Laboratory - birthplace of the atomic bomb - meant measures to prevent "human error or
malfeasance" needed to be much tighter.
Two computer discs containing classified material were found to be missing during an inventory on July 7th, and more than 2,000 vaults and safes at the laboratory are now being searched.
"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," Mr Abraham said.
Under his order, all offices using controlled removable electronic media, such as discs and removable hard drives with classified information, will shut down to take an inventory and
account for all materials.
Weekly inspections will follow, coupled with the establishment of a series of other safeguards designed to manage classified material and avoid security breaches.
"These procedures are designed to guarantee a complete inventory of our classified electronic holdings and make certain that specific individuals can be held responsible and accountable for future problems," said Mr Abraham.
The "stand-down" will begin on Monday, affecting less than half of the 59 Department of Energy facilities across the nation, a department spokeswoman said.