Britain’s farms were locked down last night and all animal movements banned again as government veterinary surgeons urgently investigated a new outbreak of foot-and-mouth disease in Surrey.

A handful of new suspect cases on other farms was also reported near fields at the centre of the alert, close to the Queen’s farm at Windsor.

Protection zones were set up and cattle culled within hours as a precaution after displaying symptoms of the highly infectious disease. Other animals were being tested and results are expected today.

Animals on a farm adjacent to the land in Surrey at the centre of the latest outbreak were being slaughtered “on suspicion” of infection, Defra said last night The Queen’s 2,200-acre Windsor Royal Farms estate – 200 Jersey dairy cattle, 2,000 pigs and 200 beef cattle – was also being checked for symptoms of disease.

One of the possible causes of the outbreak under investigation last night was that the virus may have spread unnoticed in the wild deer population or in sheep that had not shown symptoms. The Crown Estate yesterday immediately closed the deer park where animals are being monitored.

Last night, after discussions with the Department for Environment, Food and Rural Affairs, most of Windsor Great Park was closed and all horseriding suspended.

Experts yesterday gave warning that the timing of this outbreak and the ban on meat exports could be more damaging to the country than the 2001 epidemic as it is now the main season for sheep and cattle sales. The EU also announced yesterday a further complete trade ban on meat exports from Britain. A ban on exports to other parts of the world also remains.

The precise strain of the virus has not been confirmed but experts believe it is most likely to be that which escaped from the Pirbright scientific research centre – which is ten miles away – in July and sparked last month’s outbreak.

There was further speculation of sabotage or even a leak from a second government laboratory handling the virus. The Veterinary Laboratories Agency, which handles the testing for foot and mouth disease, is also nearby at Weybridge. The strain of the latest outbreak is to be identified today. If it proves to be a new virus there will be an urgent race to identify the source and spread.

The outbreak comes as New Scientist journal today publishes details of security lapse at another Insitute of Animal Health site at Compton in February. The premises are still closed after a faulty air system at a laboratory handling cattle infected with bovine TB could have exposed fourteen staff and two inspectors to the pathogen.

The European Union responded swiftly to the new outbreak and imposed a trade ban on meat exports from Britain. A ban on exports to other parts of the world also remains.

This loss of business is costing farmers £1.8 million a day and total losses so far after the August outbreak are as much as £80 million.

Some 330 Aberdeen Angus cattle owned by Robert Lawrence, of Hard-wick Park, Farm, Lyne, near Chertsey, were being slaughtered as government vets attempted to track all movements of people, animals and vehicles on his land. The investigation is complicated because Mr Lawrence owned some land and rented another six parcels of land in the immediate area. The infected cattle were on land known as Mrs Caddy’s Field owned by Milton Park Farm, an estate owned in part by a gravel company and Runnymede Borough Council.

Government vets are now desperately anxious to establish if Mr Lawrence’s premises are the centre of the outbreak or his cattle picked up disease from another source of infection lurking elsewhere. Other checks were being made on pigs in Norfolk where a temporary surveillance zone was imposed at Hindolveston, near Dere-ham. Sheep in Lanarkshire were also being tested.

Gordon Brown, who immediately returned from the Midlands to chair a meeting of the Government’s emergency committee, Cobra, rejected claims that the previous ban was lifted too early. He pledged that the authorities would do “everything in our power” both to eradicate the disease and to track down the source of the latest outbreak.

But David Cameron questioned whether pressure had been put on Debby Reynolds, the Chief Veterinary Officer, to announce last weekend that the outbreak was over.

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