Dozens of students — from what Britain calls “countries of concern” like Iran and Pakistan — have tried to infiltrate Britain’s top laboratories in order to develop weapons of mass destruction in the past year, according to an unnamed spokesman in the Foreign Office, The Guardian reported.

“There is empirical evidence of a problem with postgraduate students’ becoming weapons proliferators,” the spokesman told the newspaper, referring to students seeking graduate degrees. He added that many of the students had been intercepted under the Academic Technology Approval Scheme, introduced by universities and the security services last November.

He also said the students had been denied clearance to study in Britain under powers “to stop the spread of knowledge and skills that could be used in the proliferation of weapons of mass destruction and their means of delivery.”

The British government said its security services had intercepted up to 100 people posing as graduate students who they believe tried to get into labs to gain the materials and expertise needed to create chemical, biological, radiological, and nuclear weapons, the government told the newspaper.

Britain has about 800 such labs in hospitals, universities, and private businesses that have access to lethal viruses like Ebola and avian flu or could acquire the technology and expertise to develop deadly weapons.

An unnamed government spokesman told the newspaper that the scrutiny of foreign students seeking graduate degrees would continue with only a few of the 20,000 applications rejected for security reasons.

A spokesman for Universities UK, a body that represents universities’ vice chancellors, said the security scheme had so far proved effective. —Shailaja Neelakantan