Within five days of a new outbreak, vaccine stocks - which have been bought and stored - could be available to begin containing the disease if necessary, the Department of Environment said yesterday.
More than 2 million pigs, cattle and sheep were culled during the 2001 epidemic.
Yesterday, vets at the department revealed for the first time that they had pressed for vaccination in Cumbria three years ago, when the epidemic appeared to be out of control and thousands of pedigree cattle were being slaughtered to try to contain the outbreak.
However, the resistance of the food industry, which feared that its meat and other products would be unsaleable if the animals were vaccinated, persuaded Tony Blair to veto the idea. The slaughtering continued until the disease died out six months later.
The decision to vaccinate follows the investigation by the Royal Society, which concluded that it would be an excellent way of containing a serious outbreak.
Millions of pounds has been invested in contingency planning and building up vaccines for likely strains of the disease.
The food industry has been assured that vaccinated livestock will be fit to eat.
With international trade and tourism growing, the government says another outbreak is quite possible. "A careless person throwing a sandwich over a fence to a pig - and we could see the start of another outbreak," a department spokesman said.
"It could be this year, it might not be for another 30, but this time there will be no complacency. We are determined to be ready."
The initial policy would be for slaughter of all infected animals and all those likely to be infected from the "plume" of infection.
In pigs, this would be many miles, but it would be far shorter distances for cattle, and virtually animal-to-animal contact in sheep.
In an outbreak among cattle, the idea would be to stifle the disease by creating a buffer zone several miles wide containing only vaccinated animals around the infected area.
Once the outbreak had been contained, the vaccinated animals could be tested to ensure they had been protected from the disease. They could then be sold to market in the normal way.
The government is to carry out an exercise, codenamed Operation Hornbeam, next week to test its contingency plans.
If successful it would expect to achieve the culling all infected animals during the first few days of an outbreak and, by the seventh day, be in a position to decide whether to start vaccination.
Officials would do so only if they thought the slaughter policy was not sufficient to contain the outbreak and the disease might begin to run out of control as it did in 2001.
Ben Bradshaw, the animal health and welfare minister, said: "The role that vaccination could play in a future outbreak is a crucial area to be tested. Vaccination can be an important part of the armoury, and a great deal of work has been done by the government in turning it into a practical possibility."