London - The British government Tuesday warned of the increased threat of a nuclear or chemical attack, while unveiling plans of a greater involvement of the public in the fight against terrorism.

A government assessment of the terrorist threat said that while terrorism networks such as al-Qaeda were "likely to fragment" and might not survive in their current form, their ideology would live on.

Home Secretary Jacqui Smith, in a report to be submitted to parliament later Tuesday, said the "likely future direction" of the threat would involve the use of a so-called dirty bomb.

"Contemporary terrorist organizations aspire to use chemical, biological, radiological and even nuclear weapons," the report said.

In these circumstances, the anti-terrorism fight could not be left to the police and governments alone, said Smith, unveiling plans for a wider involvement of the public in combating the danger.

She said hotel managers and security staff would be among the approximately 60,000 workers that would be trained "in vigilance for terrorist activity and what to do in an attack."

Smith said the strategy would also tackle "anti-democratic extremist voices" in the community while supporting moderate groups which backed democracy.

People who 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" should be challenged.

"We should argue back and make clear that these things are unacceptable," said the Home Secretary.