The commission has introduced plans  to tighten security around such materials and to step up preparedness in the event of an attack.

The threat has grown alongside advances in weapons technology and increases in the use of chemical, biological and nuclear materials for legitimate purposes.

“Although Europe has fortunately not seen a large-scale attack using these materials, the seriousness of the potential consequences for our societies is such that we cannot be complacent,” said justice commissioner Jacques Barrot.

Unconventional weapons can kill or hurt large numbers of people and cause economic havoc and widespread panic.

Europe’s commitment to civil rights and open borders make it more vulnerable to an attack, as it limits the ability of governments to control people’s movements.

Based on the recommendations of an EU-commissioned task force of experts, the new three-year plan lists more than 130 measures to prevent dangerous materials from falling into the wrong hands and to be prepared if they do.

In particular, the plan calls for improvements in detection systems across Europe and new tools to save lives and limit damage in the event of an attack or incident.

The EU plan is designed to support national governments, who bear the main responsibility for security. The commission proposes to use €100m in existing funds to pay for its implementation over the 2010-2013 period.