The threat of biological weapons is real and needs to be tackled now, medical experts warn.
Anthrax is one of the threats
The British Medical Association says the window of opportunity to take action is shrinking fast.
It said the threat had intensified since it first published a report on biological weapons in 1999.
Five years on, the threat of weapons that could target specific ethnic groups is no longer theoretical and is approaching reality, says the report.
Dr Vivienne Nathanson, head of science and ethics at the BMA, said: "The situation today is arguably worse than it was when we published our last report five years ago.
"The very existence of international laws to protect us is being questioned, the anthrax attacks in the US in 2001 caused widespread panic and fear, and most worryingly of all, it's never been easier to develop biological weapons - all you have to do is look on the internet."
She said: "This report does not make comfortable reading but it is essential that governments take action on this issue now.
"If we wait too long it will be virtually impossible to defend ourselves."
The report analyses whether terrorist attacks like 9/11, anthrax attacks in the US in 2001 and the Moscow Theatre siege in 2002 have impacted on the development of biological weapons.
It concludes that if the development of such weapons is not curtailed, imitation viruses and genetically engineered anthrax could be used against people in the future.
The authors make several recommendations, including ways of agreeing and strengthening the Biological and Toxin Weapons Convention when it comes up for review in 2006.
They said governments should pass legislation to implement fully the requirements of the convention.
Scientists should be aware of how their work might impact on legal and ethical norms that prohibit the development and use of biological weapons.
If there is a danger that their results could be used in the development of prohibited weapons they should discuss this with their funders, recommends the report.
Professor Malcolm Dando, author of the study and Head of Peace Studies at Bradford University, said: "The problem is that the same technology being used to develop new vaccines and find cures for Alzheimer's and other debilitating diseases could also be used for malign purposes.
"That is why it is essential that an ethical code be developed for scientists.
"Questions need to be asked about where research could lead, where the results will be published and who has access to the data."