Prime Minister Gordon Brown cut short his family holiday to return to London to chair a meeting of the government's emergency contingencies committee and said afterwards authorities were working round the clock to curb the disease.
'We will be doing, night and day, everything in our power to make sure that what happens happens quickly and happens decisively in a way that can reassure people that everything is being done,' he said.
In line with European legislation, a national ban on moving sheep, cattle and pigs was immediately imposed in an attempt to contain the virus, which passes easily between cows, pigs and sheep but is rarely contracted by humans.
Biosecurity measures were tightened and a three-kilometre (1.7-mile) protection zone and a 10-kilometre surveillance zone were also thrown up around the farm, which is in the county of Surrey between Guildford and Aldershot, south-west of London.
The agriculture ministry told AFP it had suspended the export of meat products, animal carcasses and milk after the highly-contagious disease was confirmed late Friday.
A number of European countries responded by announcing precautionary checks on cattle, pigs and sheep as well as British livestock imports while Japan imposed a temporary import ban on pork from pigs reared in Britain.
Meanwhile, aerial television pictures showed about 60 cattle on the affected farm being herded together in preparation for what the agriculture ministry said would be a humane slaughter, followed by incineration.
The emergency recalled the last foot and mouth epidemic, in 2001, which dealt a hammer blow to rural Britain and its beleaguered agriculture industry.
Between 6.5 and 10 million animals were destroyed on huge pyres, the tourism industry was gutted, the army called in and a general election postponed while the government and authorities were criticised for their slow response.
London was quick off the mark this time around, winning praise from farmers' unions and animal health specialists.
Brown -- who has already had to deal with attempted car bombings and severe floods since taking office on June 27 -- said he was keen to avoid mass slaughter, as animal charities said such a move would cause renewed revulsion.
'We are doing everything in our power to avoid a repeat of these incidences and I do want to thank people in the rural communities for their co-operation,' he said.
'I understand the anxieties and the worries that will be there at the moment.'
Farmers and the government said they were prepared to accept the innoculation of infected animals, in a reversal of previous policy, as scientists worked to determine the exact strain of the disease and if vaccine stocks were available.
Paul Ibbot, who farms just outside the exclusion zone, told BBC radio he and other farmers in the area were looking at their animals 'with a real feeling of dread'.
'This is not anything that we can understand. Surrey is a county that doesn't have huge numbers of livestock and we just don't understand how it's here,' he added.
The 2001 outbreak cost Britain's economy an estimated eight billion pounds (16.3 billion dollars, 11.9 billion euros).
Then, some 2,000 cases of the disease were detected on farms throughout the country. Public rights of way across land were closed, hitting the tourism and agriculture sectors.
From Australia to Canada and across Europe, authorities laid out mats soaked in disinfectant at airports and ports to stop the spread of foot and mouth on footwear and car tyres, while some went even further to protect zoos and domestic livestock.
Tim Bonner, a spokesman for Britain's Countryside Alliance, said the disease could already be widespread and they 'hope and pray' there will be no repeat of six years ago.
'Tourism is the biggest industry in the countryside and right now we are at the height of the season.
'If the countryside is closed down like in 2001, this could be a disaster for thousands of rural businesses,' he told Sky News Friday night.
Foot and mouth disease owes its name to the fact that the lesions it causes are found on the inside of the mouth and on the hoofs of animals.
It is often spread on clothing, particularly shoes, but also by vehicles and agricultural tools, and there are rare examples of it having been wind-borne.