Byline: BEN TAYLOR;STEPHEN WRIGHT
SECURITY services have foiled a terrorist plot to launch a 'dirty bomb' attack on Britain.
Islamic fanatics are thought to have been planning a poison gas attack on Gatwick Airport or the London Underground.
A highly toxic chemical would have been released in a confined area with the aim of killing hundreds of people.
The substance - osmium tetroxide - causes victims to choke to death in agony and can blind. It is also highly destructive to lungs and skin.
Intelligence agents believe the chemical would have been packed around a conventional bomb, meaning some people would have died in the initial blast but many more would have been killed in the chemical fallout.
Security services in the UK were alerted to the plans when conversations about the chemical were picked up at the GCHQ listening centre.
Details of the gas plot were also intercepted by the National Security Agency in the U.S. They passed on the tip to MI5.
The phone call they overheard is thought to have taken place between Peshawar in Pakistan and Crawley in West Sussex. It increases the likelihood that an international terrorist network such as Al Qaeda was involved.
One of the targets discussed is said to be the Eurostar terminal at London's Waterloo station. But last night there were claims that Gatwick Airport and the Tube were the targets.
Details of the plot follow the discovery of half a ton of fertiliser in a selfstorage warehouse in Hanwell, West London, last week. Ten men were arrested - nine of them in the UK.
Last night U.S. securitysources confirmed that both American intelligence services and the Government eavesdroppers at Cheltenham had picked up details of a 'dirty bomb' plot.
Experts say osmium tetroxide could be 'piggybacked' on to a conventional bomb which would see the invisible chemical dispersed into a crowd. …