Iraq is not the only country to possess biological and chemical weapons, although at the moment Saddam Hussein is seen as the biggest threat.

It is estimated that there could be as many as 20 States around the world who either possess or have shown an interest in developing such capabilities.

Many of them are in the area of the Gulf, the Near East and North Africa.

And today Britain's military chiefs say that the potential threat from biological and chemical agents is now greater than that from nuclear weapons. Although weapons of mass destruction are now banned under world treaties, Saddam has already used chemical weapons against Iran and his own people.

But history shows us that this sort of terrible weapon has in fact been used on and off for many hundreds of years.

One of the first recorded attacks was back in the seventh century BC when the Assyrians used a fungal disease called ergot to poison water supplies.

Between 1754-63 there was evidence of attempts by British troops to use smallpox-infected blankets as a weapon during the French and Indian wars.

And in more recent times, during WWI, chemical weapons including chlorine, phosgene and mustard agents were used on a large scale for the first time.

In the 1950s the UK abandoned its biological and weapons capability, and today only research on defensive capabilities is carried out at Porton Down.