More than 700 foreign students have been banned from studying in the UK over fears they may use the knowledge they learn to build weapons of mass destruction (WMDs).
Student applicants to science and engineering courses have been blocked as part of the Academic Technology Approval Scheme (ATAS), which was introduced to bar extremists from accessing information and materials needed to develop the weapons.
The scheme requires non-EU students applying to certain courses to gain formal approval before they are granted a visa. Of the 20,000 applications last year, 739 were blocked.
Concerns have been raised, however, over EU and UK students who might slip through the net.
Sir John Stanley, chairman of the Arms Exports Controls Committee, told The Telegraph: "The fact 739 students have had to be barred indicates this is grounds for serious concern.
"It is extraordinary given the threat we face for the Government to go on refusing to extend this to those in the UK.
"We have made the recommendation for at least two years but it has been consistently rejected."
Rihab Taha, an Iraqi microbiologist, received her PhD in plant toxins from the University of East Anglia. She then went on to work for Saddam Hussein's biological weapons programme, and was dubbed "Dr Germ" by United Nations weapons inspectors.
Huda Salih Mahdi Ammash, who was nicknamed "Mrs Anthrax", received a masters in microbiology from Texas University and was thought to have masterminded the reconstruction of Iraq's biological weapons facilities after the Gulf War.