The large number of foreign researchers active in US laboratories would have to wear badges and laboratories would have to contain segregated work areas under the proposed code.

US universities, which have been struggling to create a more welcoming climate for overseas postgraduate students and researchers in the wake of the 9/11 clampdown, believe the measures are excessive and could offend foreign scientists.

In a memo urging its members to object to the Defense Department proposals, the Association of American Universities (AAU) said the rules could easily spread beyond areas where there may be any security concern, reported the website InsideHigherEducation.com.

The AAU noted that many universities were already experiencing "significant problems" with "troublesome clauses" in Pentagon research contracts. The association warned that the Pentagon would use the new rules to include "overly restrictive language" in many contracts.

"You're talking about a fundamental change in the whole academic environment of US universities if these kinds of changes are implemented," Robert B Hardy, of the Council on Governmental Relations, a university-advocacy group in Washington, told the Chronicle of Higher Education. "The spontaneous nature of academic research would be lost."

A survey of UK scientists found that the majority of life scientists interviewed did not believe terrorism was their problem and research should not be restricted because of potential misuse.

Brian Rappert, an Exeter University sociologist who carried out the survey, told the Times Higher Education Supplement that work on infectious disease should prompt security questions.