The government will use text messaging to alert the public to a biological or chemical attack in the UK.

Nick Raynsford, the minister responsible for terror contingency planning in London, said the emergency services, the broadcast media and the mobile telephone network would be used in the event of a terror attack.

"What we have been trying to do is put in place arrangements that will ensure in the event of any incident that there is a very effective communication network using all available channels to reach people and give them the messages that they will need to have," he told the BBC.

"There are a whole range of different elements all being planned - some of which will fail because in certain circumstances certain networks will not be operational."

But he dismissed calls for the government to publish details of how the public should respond in the event of an attack.

Raynsford said there were risks in being "too open" about the threat.

"We have to tread a very fine line here. I am conscious that people are frustrated they don't necessarily know enough," he said.

But he added it was "very difficult to give people in advance information about all possible eventualities".

"What we trying to ensure is that people know that arrangements are being put in place to try and guard against eventualities without panicking people," said Raynsford.

"Remember one the terrorists' main objectives is to disrupt society and if they can engender a sense of panic that will achieve their own ends."