Cobra, the Government's emergency committee, is meeting in response to the outbreak of foot-and-mouth disease.

Prime Minister Gordon Brown and Environment Minister Hilary Benn cancelled their holidays to return to London to deal with the infection on a farm near Guildford, in Surrey.

The Department for Environment, Food and Rural Affairs (Defra) has imposed a three kilometre "protection zone" and a 10 kilometre "surveillance zone" around the farm.

A nationwide ban on the movement of all sheep, cattle and pigs has also been put in place. All the cattle on the infected farm are to be killed.

First results from the scientific analysis of the virus could be available as early as late Saturday, although it may take longer depending on the exact strain of the virus involved.

Once the strain has been identified, experts will check to see whether relevant vaccines are available in the British or European vaccine banks.

The outbreak raised the spectre of the foot-and-mouth epidemic of 2001, which brought chaos to Britain and left farming and tourist industries devastated. It led to the slaughter of between 6.5 and 10 million animals, ruined many rural businesses and is estimated to have cost the country up to £8.5 billion.

On Saturday a Defra spokesman said work was continuing at the farm and refused to comment on whether any other farms were involved.

The Defra spokesman said on Friday night: "Following an investigation of suspected vesicular disease by Animal Health on a holding near Guildford in Surrey, laboratory results have indicated that the foot-and-mouth disease virus is present in samples from cattle on the premises. On the basis of initial laboratory results, Debby Reynolds, UK Chief Veterinary Officer, has confirmed foot-and-mouth disease.

"Nationally no animal movements are allowed except under licence, controls are in place on movement of animal carcasses, animal gatherings, shearing and dipping are restricted, and all farms must increase levels of biosecurity."