'Pakistan has legislation in place as a nation to establish this type of capability and maintain it. They have developed their own lists of materials and advanced their lists of materials on things that they are looking for,' he added.

Responding to a question from Congressman Niki Tsongas, D'Agostino agreed with a recent report by the Commission on the Prevention of Weapons of Mass Destruction Proliferation, which concluded that Pakistan as a focal point of terrorism and weapons of mass destruction.

'I would just add that collaboration of the Pakistani government with the US is a sensitive matter in Pakistan. So what we do with them is best discussed elsewhere,' said Michael Nacht, assistant defence secretary for Global Strategic Affairs, who also testified before the Congressional committee.