Anthrax tested on London Tube

Anthrax letters caused chaos in Washington last year

By the BBC's Rick Fountain

Previously secret UK Defence Ministry files just released in London reveal that British scientists tested how anthrax might be spread in the London Underground railway.

The research carried out in the 1960s found that a couple of hours after being released, spores of a bacillus - harmless to humans but resembling anthrax - had travelled nearly 30 kilometres along the tunnels.

The cover page of one of the hitherto secret files now made public

Spores were released in walkways between platforms and from train carriage windows.

The scientists concluded that the spores that travelled furthest were carried inside trains.

Two sets of trials were carried out, in July and August 1964, at the southern end of one of London's longest underground rail tunnels, the Northern Line, at Colliers Wood and Tooting Broadway.

In one test, scientists from the Porton Down research establishment released about 30 grams of the spores in an underground walkway between platforms.

In the other, the spores were dropped from a carriage window as the train gathered speed.

Spores travelled far

Quantities of the spores were found an hour or two later at Northern Line stations in central London and even Camden Town in the north of the city - a distance of about 18 kilometres.

In the second test, involving a smaller quantity, spores were found even further north - at Highgate.

The files suggest further trials were planned - but details have not yet emerged.

Five people died in the United States last year after being infected with anthrax from a series of contaminated letters, some of which were mailed to prominent public figures.

A 1993 report estimated that releasing a cloud of 100kg of spores upwind of Washington DC could cause between 130,000 and 3m deaths.