FBI joins nuclear secrets hunt

Fires forced the closure of the laboratory last month

FBI agents have joined the hunt for classified nuclear weapons data which has vanished from a top US research centre.

The information - which includes details on disarming nuclear bombs - was stored on computer hard drives at the Los Alamos National Laboratory, New Mexico.

The data vanished when staff were forced to flee from a devastating forest fire in May, according to US media reports.

The laboratory was heavily guarded during the blaze

Staff now face lie detector tests, as the FBI agents and officials from the US Department of Energy try to trace the missing drives.

"This is an extremely serious matter and we are taking swift action to deal with it," said John Browne, the laboratory's director.

Lie detector

Staff who could have had access to the material or the vault where it was stored are to be given polygraph tests, said Ed Curran, director of counter-intelligence at the Energy Department.

But he stressed there was nothing to suggest that the hard drives had been stolen by spies.

"At this point, there is no evidence that suggests espionage is involved in this incident," said Mr Curran.

At this point, there is no evidence that suggests espionage is involved in this incident

Counter-intelligence head Ed Curran

The hard drives, said to have been stored in a suitcase, gave details on how to respond to nuclear accidents and nuclear-related threats from terrorists.

There was also material on the Russian nuclear weapons programme.

"These hard drives are very heavily protected but the information is intended to be moved, because they're used by our nuclear emergency search teams to respond to incidents around the globe on a 24-hour basis," Mr Browne said.

He said it was not clear whether national security information had been compromised by the disappearance.

The laboratory has been embroiled in a spying controversy involving a former employee for much of last year.

Wen Ho Lee's daughter protests his innocence

The scientist, Wen Ho Lee, was arrested and charged in December for misuse of secret nuclear data.

He is still awaiting trial, and officials are not said to believe there is any link between the charges against him and the disappearance of the hard drives.

One theory is that, in the chaos of the forest fire and its aftermath, the drives have simply been mislaid.

Republican Senator Frank Murkowski, who chairs the house committee on Energy and Natural Resources, said that even if the drives were lost rather than stolen, the issue must be taken very seriously.

"It gravely concerns me that they have even been displaced," said Mr Murkowski.

"If they can't keep track of this kind of information, it raises serious conerns about overall security."