A Bradford lecturer has unravelled the secrets of biological warfare with a book calling for more stringent rules on development of the weapons.

Dr Simon Whitby says regulation of biological weapons is too lax and will relay his fears at a United Nations (UN) conference in Geneva on November 17.

His book, Biological Warfare Against Crops, investigates state- run programmes on developing the weapons but he does not believe attacks against sources of food would be a tactic employed by terrorists.

Dr Whitby, based at the University of Bradford, said: "There has been a lot of speculation about the origin of the pathogen used in the anthrax attacks.

"But what we have been looking at since the attacks of September 11 is mass casualty terrorism - I wouldn't think terrorists aiming to attack people would also attack food crops."

The book outlines how countries, including the US, former Soviet Union and Britain, have conducted tests into using biological weapons to attack crops and says that at the height of the Cold War, America claimed it had enough stockpiles to send its Communist enemy into famine.

Dr Whitby, with the university's peace studies department, is an adviser to the UN's Ad Hoc Group which is overseeing moves to strengthen the protocol surrounding biological weapons.

He is also webmaster for the University's project on strengthening the protocol and has published numerous articles on biological warfare and its control.

He said: "At the moment we have a weak international prohibition against developing biological weapons which we have been trying to strengthen for the last seven years but was hampered when, earlier this year, the US walked out of talks.

"They claimed the protocol was not strong enough after having spent the last seven years trying to get it watered down.

"We need a mechanism which checks research into biological weapons and prevents states from breaking the agreement, as the former Soviet Union did in the 1970s."