UK customs are investigating a possible criminal offence involving weapons of mass destruction, MPs probing arms exports controls have been told.
MPs are probing arms exports
Mark Fuchter, of HM Revenue and Customs, said it was expected the case would be reported with a view to prosecution.
Those involved were not in custody yet but the operation had been disrupted, he told a House of Commons committee.
The committee is investigating controls on arms exports.
Mr Fuchter said it would probably be proposed that charges should be pressed for offences committed under the anti-terrorism Crime and Security Act.
It would be the first case using new powers imposing penalties on British nationals for some offences committed abroad that involve trafficking in torture equipment or long-range missiles.
Pressed by the former Conservative defence minister, Sir John Stanley, Mr Fuchter confirmed that the investigation involved components or materials related to weapons of mass destruction.
Sir John said the case was "clearly of profound significance" and he wasn't aware that it had previously appeared in the public domain.
Mr Fuchter could not say when a prosecution might be launched, adding that there were "particular challenges" over the evidence.
But witnesses told MPs they were confident that the person or persons involved were no longer able to continue their illegal activities.
Asked by Sir John Stanley if that meant they were confident that public security was not now at risk, Mr Fuchter said: "Our view is that the operation has been thoroughly disrupted."
He confirmed however that the individuals involved were not in custody.
The MPs are on the Quadripartite Committee, which is made up of members of four Select committees: Trade and Industry, Foreign Affairs, Defence, and International Development.