Britain faced the prospect of a foot-and-mouth epidemic and a mass slaughter of animals on a scale not seen since the 1960s as a 12th case of the disease was confirmed last night.
At the same time it emerged that as many as 25,000 sheep, cattle and pigs may have passed through three markets at the centre of the outbreak before the ban on moving livestock came into force.
The Chief Veterinary Officer, Mr Jim Scudmore, confirmed that investigators were tracing the movements of all animals, vehicles and people out of the markets - at Hexham, Long town near Carlisle, and Northampton - as diseased animals were believed to have passed through all three.
The latest case, at Okehampton in Devon, confirmed the dramatic spread of the disease from the north-east of England to the south-west, home of the highest concentration of livestock in the country.
As continental Europe went on alert, farmers' leaders held emergency talks with the Prime Minister, Mr Tony Blair, at Downing Street - emerging afterwards to tell of the "despair, desperation, fear and absolute horror" of their members at the developing crisis.
In the Commons, the Agriculture Minister, Mr Nick Brown, spoke of the government's determination to exterminate the disease before he left for Brussels to brief other EU ministers. While pledging to support all government measures, the Conservatives said they would ensure a half-day debate on the crisis later this week.
Following Sunday's discovery of the disease at Highampton, Devon, any lingering hope of controlling the situation evaporated with the emergence of five new cases, two in areas previously unaffected.
A five-mile exclusion zone was thrown around a farm in Westerhope, Northumberland. It is believed the disease found on cattle at the farm was spread on the wind from the Heddon-on-the-Wall pig farm some five miles away, believed to be the source of the outbreak.
As the mass burning of cattle continued on farms across the country, Dartmoor was declared a "no-go" area in the wake of confirmed cases of foot-and-mouth near the National Park.
Yesterday's race meeting at Newcastle was cancelled, as zoos across the country, and three royal parks in south-west London, were closed.
The pro-hunting Countryside Alliance cancelled its planned march on London next month, while the government considered the temporary closure of footpaths to stop ramblers spreading the disease. Doubt was also cast on Saturday's rugby international between Wales and Ireland in Cardiff.
With hopes of containment and speedy eradication fast disappearing, it emerged last night that Britain's livestock farmers could suffer from the temporary ban on exports for at least six months after any declaration that the country is free of foot-and-mouth.
The Chief Veterinary Officer said in practical terms Britain could be declared free of the disease within 21 days of the destruction of the last infected carcass. However, he admitted foreign importers would be looking for longer that the recognised three-week incubation period.