SCIENTISTS at Porton Down have developed an antidote to the poison ricin and say it is ready to be manufactured.

The breakthrough is the result of eight years’ work at the Defence Science and Technology Laboratory.

Ricin is the poison that was used on the tip of an umbrella to murder Bulgarian dissident Georgi Markov in London in 1978.

It is 1,000 times more toxic than cyanide, and fears have been expressed that it could be used by terrorists.

The antidote can protect against death up to 24 hours after exposure to the poison, according to DSTL’s Dr Jane Holley, principal scientist in biomedical sciences.

She said: "In the past there has been lots of research carried out using different methods. But this is the first anti-toxin that has been moved into production.”

The antidote developed at Porton was initially intended for use by the military, but the scientists are investigating its potential use in a civilian environment.

Its production involves immunising sheep with an inactive form of ricin, which causes them to produce antibodies.

These are harvested from the sheep to produce a freeze-dried antidote, which can then be reconstituted with water for injection into the body.

Dr Holley said full licensing of the product is likely to take about five years.