People are being advised by the government to "go in, stay in, tune in" in the event of a terrorist attack on the UK.
Stock up on basic supplies, the Home Office advises
But the advice has been criticised by one terrorism expert as being in danger of doing "more harm than good" by alarming people.
In an updated website launched on Wednesday, the Home Office is telling people to go indoors and listen for specific instructions which will be broadcast on the radio.
It says take "sensible precautions" such as having battery powered torches, radio, ready to eat food, bottled water and blankets close to hand.
The department says there is no need at present to take further measures such as stockpiling food or buying a gas mask.
Home Secretary David Blunkett said the website was designed to give clear advice on the specific threat of terrorism to the UK.
"The threat from terrorism remains real and serious," the website advises.
"It now comes not only from established groups with clearly defined targets, but also from unaffiliated, loose-knit networks of individuals with a much broader agenda.
"The principal threats come from international terrorism, and in particular, extremist groups, including those who erroneously claim to be acting for Islam; and nationalist, separatist, and other violent terrorist groups. We do not see the Muslim community as a threat."
A more comprehensive dedicated website will be launched shortly, the government said.
In terms of self-protection, the Home Office advises the public to be above all vigilant.
"Trust your instincts; if you feel something is wrong, ring the police," it said.
Terrorism expert Mike Yardley said a lot of people would be frightened by the website announcement.
"The probability is that it will cause more psychological impact and play into the enemies' hands," he said.
The suggested measures would make no difference if an attack involved a large scale device, he said.
Former anti-terrorist officer Charles Shoebridge told BBC News Online the government website advice was "next to no use".
"In a way its just building up people's worries and fears - but without providing concrete information, " he said.
The director of St Andrew's University's Research Institute for the Study of Terrorism and Political Violence, Professor Paul Wilkinson, said the advice was sensible, not alarmist.
"The advice would, however, have to be followed up in more detail in the event of intelligence indicating a particular type of attack", he added.
The website's advice includes:
Be aware of your surroundings both at home and at work, so you know if something is wrong or out of place.
At work, know your staff and suppliers.
The site has echoes of the 1980s "Protect and Survive" advice
Take care of financial information so credit cards and bank accounts cannot be stolen by terrorists.
Have contingency and escape plans at work and practise them.
Protect against electronic hacking and tighten security both at home and work.
Mr Blunkett said he understood the public's need to know more about the terrorist threat.
But he said often the government was not able to answer all their questions because it might pose a security threat.
"But the public have a right to have their concerns addressed, and to know as much as possible about the work that goes on behind the scenes to protect them," he said.
"I am committed to putting as much information as I can in the public domain, without compromising security."
Mr Blunkett said the website would be used to issue specific warnings about targeted venues or threats.