False alarms are psychologically damaging, say experts
Terrorist threats from conventional, nuclear, biological or chemical weapons are covered in the guidelines, released amid a series of anthrax false alarms around the UK.
The UK's chief medical officer Professor Liam Donaldson said there was not thought to be "any real threat" to the population, with the US the only place to confirm cases of the disease since the terror attacks.
Home Secretary David Blunkett is looking at extending the maximum penalty for hoaxers from six months to seven years - putting them on the same level as bomb hoaxers.
He said he wanted to take decisive action so people's lives were not disrupted.
'Psychological weapon'
Prof Donaldson said updated guidance to health professionals included advice on botulism, plague, small pox, as well as anthrax.
He said images of fire crews in space suits "give the terrorists what they want - creating fear".
But, urging the public to remain vigilant, he added: "Anthrax is not a particularly good biological weapon but a hugely successful psychological weapon."
Chief Superintendent Kevin Morris, chairman of the Police Superintendents' Association, told the BBC hoaxers would be pursued through the courts if caught.
There were a further series of false alarms on Wednesday, including evacuations after suspect packages were found by postal workers in Hatfield and Chelmsford.
Downing Street says the latest guidance to health professionals is complementary to guidance sent out last week.
'Be alert'
Chief Superintendent Morris said anyone receiving a suspicious package in the post should take it seriously and put it somewhere safe, seal the room, stop anyone going in and call a police station for advice.
Prime Minister Tony Blair's official spokesman has urged the public to "retain a sense of perspective".
"We understand why people are concerned when they see events in the US," he continued.
"People should not be unduly concerned - but it is important for the government to make appropriate contingency and public health planning arrangement, which is what we are doing."
British charity Sense - which works with peopel who are both deaf and blind - cancelled a fundraising mailshot to 20,000 people on Wednesday, because it contained a sachet of bath salts.
False alarms
Emergency services were called to the Royal Mail sorting office in Hatfield on Wednesday after a suspect package was found by workers there in the early hours of the morning.
Police said there were no injuries and there was no cause for alarm, although six staff underwent a cleansing procedure and checks at the local hospital.
Birmingham's Royal Mail sorting office was evacuated on Wednesday evening.
Several hundred workers gathered outside the building while police dealt with a suspicious package.
A spokesman said there would be delays on Thursday to deliveries in the city and to post going from Birmingham to the rest of the country.
Up to 30 BBC employees were decontaminated as a precaution after a suspect package was discovered at Bush House, in London.
Part of the building was closed during the incident just after 1630BST.
Police, ambulance and fire crews attended the scene.
Officers in specialist clothing took the package away for tests, a Scotland Yard spokesman said.
Incidents in London and Liverpool on Tuesday all proved to be harmless.
Police gave the all-clear at Liverpool's Royal Mail sorting office, which was evacuated after a suspect powder - later found to be sand - was discovered at the site.
A suspect package which saw the London Stock Exchange evacuated was later found not to contain any trace of anthrax.
White powder
In Essex on Tuesday night, the sorting of overnight mail was disrupted after a suspect package prompted the evacuation of over 700 Royal Mail employees from the sorting office at Boreham, near Chelmsford.
Police and fire crews were called to the scene and two hours afterwards declared the area safe.
In London police were called to the Middle East Broadcasting Centre after a suspicious letter containing white powder was sent to the Head of News.
There were also alerts at postal sorting offices in Preston and Bradford.
And the third floor of the 20-storey Driver and Vehicle Licensing Agency headquarters in Swansea was evacuated and sealed off after a suspect package was spotted in the post room.
There was also a false alarm at Millbank in London - where the BBC has studios - at about 2035BST on Tuesday.