In the past 30 years biotechnology has been revolutionised by molecular biology and genetic engineering. These techniques, used to control infectious diseases, can also be used to create more effective biological weapons.

Speaking at the conference on the future of weaponry, Professor Kathryn Nixdorff, of the University of Darmstadt, said that dangerous micro-organisms had already been produced inadvertently during attempts to modify vaccines and viruses.

Russian researchers had created a strain of anthrax bacilli capable of evading immune mechanisms: hamsters injected with the engineered strain were not protected by the usual anthrax vaccine.

Australian researchers trying to develop a vaccine to prevent pregnancy in mice stumbled upon a new and more virulent form of mousepox virus which inhibited the production of a class of lymphocytes needed to combat the infection.

Although humans were not susceptible to infection by mousepox virus there was concern that the human pox virus could be similarly manipulated to make it more deadly.

There were several ways in which modifying micro-organisms had potential military use. Bugs could be given a resistance to antibiotics, they could be made more resistant to the environment and thus longer lasting, and they could be made more lethal.

But she dismissed the suggestion that information gained from the sequencing of the human genome could be used to create a biological weapon specific to a particular racial or ethnic group.

"At present this seems unlikely for several reasons," she said. "It has been pointed out in several reports that races do not exist from a genetic perspective; there is generally more genetic variation within groups than between groups.

"Indeed, it has been suggested that a re-examination of the race concept is due."