This two-part series lays bare the threat from chemical and biological weapons - weapons which politicians and military chiefs now see as posing a greater threat than nuclear arms.

For decades, the United Nations and its agencies have attempted to spread the world's dealiest technologies i.e. those used to make weapons of mass destruction.

But a BBC investigation reveals a system in crisis and exposes a network of of shadowy scientists and companies involved in the deadliest trade of all.

Read more:

Britain "knew about nuclear network"