American officials investigating the disappearance of classified information from the nuclear weapons laboratory at Los Alamos in New Mexico are to give staff there lie detector tests.

Two computer hard drives were found to be missing from a vault at the laboratory when staff went to retrieve them during a forest fire that was threatening the complex.

The head of security at the department of energy, retired general Eugene Habiger, told a congressional committee he believed the information had been misplaced rather than stolen.

The US Energy Secretary, Bill Richardson, has set up a bipartisan investigation into the incident, headed by two senior politicians -- former Republican senator Howard Baker and a former Democrat representative, Lee Hamilton.

From the newsroom of the BBC World Service