War against terrorism: Alert

Stockpiles of antidotes to biological and chemical weapons were being taken out of storage for use by the country's hospitals and GPs yesterday as Britain's defences went on alert.

The Department of Health said it was consulting NHS administrators and emergency public planners all over the country in preparation for any attack using anthrax or other deadly diseases. While urging the public to remain calm, the department and the National Public Laboratory Service (NPLS) put 35,000 GPs on notice of the potential for the deliberate release of anthrax and advised them on how to treat it.

Three Britons being tested for the disease after visiting buildings in Florida and New York, where several Americans were infected, are thought to be showing no symptoms but are being treated with antibiotics. The level of concern remained high after weekend scares.

Last night Canterbury Cathedal was closed and about 200 people were evacuated after reports that a man of Arab appearance let loose some white powder in a chapel within the crypt area. Despite an intensive search for the suspect no arrests had been made. A sample of the powder has been sent for analysis.

On Saturday, emergency services were called to a railway station in Enfield, north London, after a "chemical incident" in which passengers reported feeling unwell, although nothing was found.

The Health Department would not confirm reports that more than 50 million doses of antidote to anthrax were being made ready, but it did say it was preparing for any attack.

In the case of anthrax an "antidote" as such would not be necessary; the disease is quite successfully treated with a number of types of antibiotic, the most efficacious regarded as ciprofloxacin, which the NPLS also recommends for plague and tularaemia. "We're not saying what antidotes we have or in what quantities for security reasons, but we can confirm that we have strategic stockpiles to treat chemical and biological attacks," the Health Department said.

The Public Health Laboratory Service has also called on vets in Britain to provide an "early warning system" of the risk to humans by watching for signs of anthrax in any grazing animals that they treat.