The Chief Medical Officer has said the Government was prepared for the possibility of an anthrax attack.
Professor Liam Donaldson stressed that there was no evidence of an "immediate threat or risk" but revealed antibiotics had been ordered in the last fortnight in an effort to counter the disease.
"We don't have any evidence that there is any threat or risk but it is our responsibility to plan and plan well – and that is what we have been doing over the last two weeks," he told BBC Breakfast.
The Government had secured the "necessary stores" of antibiotics and other equipment, he said, and pinpointed the need for detailed "scenario planning" over the coming months and years in collaboration with the US.
The measures were in addition to guidance issued by the Government on how to counter any possible threat from biological or chemical agents.
Asked if the Government was prepared for a biological attack, Prof Donaldson said: "I think we are very well prepared. We have one of the best public health systems in the world."
His remarks came as the number of people in the US who either have anthrax or have been exposed to it rose to 12.
In Britain three people who worked in buildings in the US where anthrax was detected are waiting for the results of tests.
US Health Secretary Tommy Thompson described the attacks an "act of terrorism".
Fears of biological attacks grew after spores were found on a police officer and two lab technicians investigating an anthrax–contaminated letter sent to NBC television's studios in New York.
A second NBC employee is also taking antibiotics after displaying possible symptoms of the disease.
Mr Thompson said that he considered the anthrax cases in New York, Nevada and Florida to be instances of bioterrorism.
But US Attorney General John Ashcroft said it was too early to say if there was a direct link to Osama bin Laden, chief suspect in the devastating hijackings in New York and Washington last month.
As panic grew in the US, several other media organisations reported potentially infected mail, including the New York Times and CBS in Washington DC.
However, in Nevada officials said four people who may have come into contact with a contaminated letter at a Microsoft office tested negative while results were not known for two others.
Two of the people in Britain being tested currently worked at the newspaper offices in Boca Raton, Florida, where five employees have already tested positive for exposure to the disease following the death of a British–born worker there.
The other was in New York where Erin O'Connor, 38, an assistant to NBC news anchorman Tom Brokaw, was exposed after opening a letter addressed to her boss and finding a powdery substance.
The Department of Health said it contacted all GPs last week to remind them how to access latest advice on diagnosing anthrax.
The Public Health Laboratory Service has also produced new guidelines for doctors dealing with any anthrax case.
The United States consulate in Melbourne, Australia, was evacuated today after a suspicious chemical was found in a letter.
Authorities evacuated a terminal at Vienna's international airport after a suspicious–looking white powder was found at a news stand.
The terminal was later reopened and there were no serious flight disruptions.
British Medical Association scientific officer Dr Vivienne Nathanson called on the Government to give doctors more information about potential bioterrorism threats.
"The most important thing that they can do is give GPs the information that they can give to patients so the patients can be reassured that the Government has done all that is appropriate," she said.
"At the moment, so much secrecy clouds the issue that it is difficult for GPs to give the reassurance that is needed.
"The public want to see that the Government has looked into the possibility of all different sorts of biological warfare and made appropriate vaccines available," she told the BBC Radio 4 Today programme.
The FBI have confirmed a "clear link" between the terrorists targeting the US and American Media Inc, the newspaper offices in Boca Raton hit by the anthrax scare.
The wife of The Sun editor – part of the company's tabloid chain – rented two apartments at Delray Beach, Florida, to two hijack suspects killed in the September 11 suicide missions.
The Sun employed British–born photo editor Bob Stevens, who died this month from anthrax.
Sun editor Michael Irish's wife, Gloria, a real estate agent, rented properties to Hamza Alghamdi and Marwan al–Shehhi this summer, according to FBI spokeswoman Judy Orihuela.
Al–Shehhi and Alghamdi were on United Airlines Flight 175, the second jet to strike the World Trade Centre.
"There is now a link between the editor's wife and the terrorists," Ms Orihuela said.
But she added that FBI was not drawing immediate conclusions.
"Right now, it looks like a coincidence. We are not searching the apartments at this time. We are focusing on this building."
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies