British agriculture is holding its collective breath.

The Agriculture Minister, Nick Brown, after meeting farmers' leaders, confirmed this lunchtime that no new cases of foot-and-mouth have emerged beyond the ten-mile exclusion zone in Essex.

All the farms whose animals were sent for slaughter to the Cheale Meats abattoir near Brentwood are under close scrutiny. Tests are being carried out in Ireland, too, and so far all have proved negative.

The blanket ban on all exports of meat and live animals is regarded by the industry as an unavoidable burden - and farmers can only hope that it doesn't last too long.

How long depends crucially on containing the outbreak - not an easy thing to do when the virus is such a resourceful traveller in live and dead meat, by human transmission or floating for dozens of miles in the air.

NFU expresses hope

One of the NFU representatives at this morning's meeting with Nick Brown told the World At One that he believes that the export ban could be lifted by early March.

Kevin Pearce, the organisation's chief livestock adviser, said that even after a short delay, it would be necessary to rebuild the lost trade.

Pigs, cows, sheep and goats can catch the virus

Certainly no concessions are likely to be made by our trading partners.

North America and several countries in Asia have already banned all imports of British meat. Indeed there is what amounts to an international consensus on the need to place countries in quarantine as soon as an infection is confirmed.

What's less clear is how well policed those arrangements are. Much speculation has already focussed on the last major outbreak at the end of last year - in South Africa - especially since it involved the same strain of foot-and-mouth.

An imported virus?

If contaminated food is the source...it is very difficult to see how that could have come into the country legally

Nick Brown

The NFU has been quick to suggest that the answer may lie in food or animal feed imported from countries with lower standards than ours.

Discovering the source of the outbreak is not just an academic exercise. It will form an important part of the efforts to stamp out the disease.

Dr Alex Donaldson, of the Pirbright Laboratory at the Institute of Animal Health in Surrey, a specialist in foot-and-mouth disease, told the programme that the greatest threat of the disease spreading came from the movement of live animals.

At this stage, to point a finger at any particular source outside the UK...seems to me to be quite premature

EU Commissioner David Byrne

But he warned: "The incubation period for foot-and-mouth disease in the extreme can be as long as two weeks."

But problems could also arise from contaminated meat or animal feeds. One possible source was South America, following recent outbreaks in Argentina and Uruguay.

Industry will be hard hit

With so much uncertainty in the air, the food industry can only guess how much the outbreak will cost. The meat export ban will mean losses of about �8 million a week - but the domestic market too, worth a quarter of a billion pounds - could also be seriously damaged.

Brown held meetings today about the crisis

The Food and Drink Federation says that a 'worst-case scenario' could mean losses of �50 million. The Livestock Auctioneers Association said this morning that the price of live animals has already fallen by 25%.

Compensation has been promised only to farmers whose herds have to be slaughtered. Those affected by falling prices and movement restrictions, though, will find it harder to get relief.