The British government has warned that the threat of a terrorist attack on the UK involving chemical or nuclear weapons is now more realistic.
British Home Secretary Jacqui Smith was speaking as she published a new counter-terrorism strategy outlining the causes and possible future direction of the terrorist threat against Britain.
Today's document, called Contest Two, is the first unclassified document to publish a detailed assessment of the threat against Britain.
It warns of the likelihood of an attack using a so-called dirty bomb, saying that terrorist organisations now aspire to using chemical, biological or radiological weapons.
Three-quarters of the most serious terrorist plots now being investigated in Britain have been linked to Pakistan, although today's document suggests that al-Qaeda in its current form is likely to fragment into smaller groups motivated by a broadly similar ideology.
One senior Home Office source said today that the size of Britain's secret service had doubled in the past three years and that there were now over 3,000 police officers working exclusively on counter-terrorism.
