UK faces greater threat of 'dirty bomb'

Terrorist attack plans 'more realistic than in the past', Home Office warns

Britain faces an increased threat of a chemical, biological or nuclear attack, ministers warned yesterday as they published the most detailed account to date of the country's strategy for countering terrorism.

They warned that terrorist hopes of using a nuclear "dirty bomb" or other devastating chemical or biological weapons were "more realistic than it may have been in the recent past".

A 171-page strategy document drawn up by the Home Office, based on declassified intelligence assessments, also warned that terrorists have developed new explosives and might try to use improvised bombs on British soil. Home Office ministers called for greater emphasis on working with the Muslim community to challenge the ideas behind violent extremism and addressing grievances exploited by radicals. Jacqui Smith, the Home Secretary, said the Government should "argue back" if groups try to undermine British values.

She said: "We have said that, where people may not have broken the law but nevertheless act in a way that undermines our beliefs in this country in democracy, human rights, tolerance and free speech, there should be a challenge made to them, not through the law but through what we are calling a civil challenge. We should argue back and make clear that these things are unacceptable.

"I believe that the vast majority of communities from all different religious and other backgrounds in this country support those shared values and also want to make that challenge."

The report revealed that al-Qa'ida had established research centres working on chemical, biological and radiological weapons in Afghanistan during the rule of the Taliban and said "large numbers" of the group's members were trained in the use of poisons.

Al-Qa'ida cells in Britain considered the use of radiological weapons in 2004, the report said. In 2003 the group developed a device to produce hydrogen cyanide gas, and in 2007 it used bombs with chlorine gas cylinders. The report pointed to the availability to technical information about the deadly weapons on the internet and said the spread of "dual-use" materials used in nuclear energy, medicine and bio-technology increased the risk that they could be used by terrorists. It also warned there had been "a significant increase in the trafficking of material which can be used in radiological weapons as well as potentially in nuclear weapons".

It said: "Contemporary terrorist organisations aspire to use chemical, biological, radiological and even nuclear weapons. Changing technology and the theft and smuggling of chemical, biological, radiological, nuclear and explosive materials make this aspiration more realistic than it may have been in the recent past."

Asked yesterday whether the threat of a chemical, biological or radiological attack was greater now than five years ago, Ms Smith said: "There is the potential, given the international situation, what we believe to be the aspirations of some international terrorists, that it could be. Failed states, conflict, technology – both in terms of the ability to use materials and the ability to learn about how materials are used – contribute to our concern about that as a threat, including what we know about what terrorists may have previously planned to do and may be planning to do."

Chris Grayling, the shadow Home Secretary, said: "We have argued strongly that the Government is not doing enough to tackle the problem of individuals and groups in the UK who are fostering the extremism that lies behind the terrorist threat. That really does have to change."