EGG producers in Herefordshire and neighbouring counties could see a boost in sales following the growing evidence of a Spanish link in many salmonella cases in the UK.

The health concern has prompted the Food Standards Agency to warn importers and wholesalers that eggs from Spain must be heat-treated and there is also a call for an emergency ban on the import of Spanish eggs.

So the little lion stamp on eggs, which assures the housewife that UK laying birds have been vaccinated, is expected to play a more significant role in persuading housewives to buy British.

However, not all salmonella cases are linked with imported eggs, says Alan Edwards, poultry advisor for the National Farmers Union in the West Midlands, who points out that although poultry in the UK may be vaccinated against salmonella, the disease would always be present and would multiply if conditions allowed.

Mr Edwards emphasised that many smaller producers in counties such as Herefordshire, who did not necessarily sell lion-stamped eggs, ensured their flocks were vaccinated. "The UK market, including the lion-marked eggs, will be strengthened but it is unrealistic to entirely blame the Spanish as salmonella may be on the egg rather than inside and could multiply in dirty kitchens."

Mr Edwards said that in general large producers belonged to the British Egg Information Council and had their eggs stamped with the lion.

"Unfortunately, because of the strong £ it is cheaper to buy imported products and large amounts are coming in."

Stricter rules for egg production were being introduced in 2004, he added.

A call for an emergency ban on the import of eggs from Spain has been made by David Lidington, the Shadow Secretary of State for the Environment Food and Rural Affairs. There should be a ban until a reliable system of testing was in place, he said. "Britain's egg producers follow stricter hygiene and disease control rules than their competitors. They deserve a fair deal in the market place. Ministers and the Food Standards Agency should take action over imports."