Scientists and research students working with dangerous biological agents may in future have to undergo vetting to prevent terrorists acquiring weapons of mass destruction, Foreign Office officials revealed today.

Patrick Lamb, the deputy head of the Foreign Office non-proliferation department, said the large number of researchers - many from overseas - working in British laboratories on potentially lethal germ agents was a "major problem".

The head of the department, Tim Dowse, said in evidence to the Commons foreign affairs select committee that a system had already been set up for universities and other institutions to notify the Foreign Office of any students from "countries of concern" who registered for particular scientific courses.

This system was put in place after the discovery that the head of the Iraqi biological weapons programme, Rihab Taha, had studied for a doctorate on plant pathogens at the University of East Anglia in Norwich in the 1980s.

But Mr Dowse acknowledged that the system was only voluntary and that not all institutions had signed up for it.

"It is not universal," he told the committee.

"We encourage institutions to let us know if they receive an application from a country of concern to a course of concern."

Mr Lamb accepted that there might now be a case for strengthening the controls with the introduction of some form of vetting of individual students.

"We recognise this is a major problem," he said. "Perhaps we need to consider actual vetting to make sure the individuals don't use the information they acquire."

In the past universities have resisted such controls on the grounds that they would encroach on academic freedom.

Mr Dowse told the committee that the Foreign Office had no evidence that any terrorist group, such as Osama bin Laden's al-Qaida network, had succeeded in their attempts to acquire chemical or biological weapons.

"There are certainly terrorist groups that are interested in acquiring chemical or biological weapons. There are terrorist groups, including al-Qaida, that have taken active steps to acquire them," he said.

"We have no evidence at this moment that they have succeeded."