Contaminated illegal foreign meat smuggled in for the restaurant trade may have set off the foot-and-mouth crisis, the British government said yesterday.
Britain's Agriculture Minister, Mr Nick Brown, discussing how the infection may have entered the country, said one possibility was through illegal commercial imports of meat.
Another was that infected produce might have entered as a "personal import" and that this was subsequently incorporated into pig swill.
Officials believe contaminated meat, possibly imported illegally for use in Chinese restaurants, is to blame for the epidemic.
Mr Brown said it was likely the initial source of the outbreak was the farm at Heddonon-the-Wall in Northumberland. The farm was licensed to feed swill to pigs, but, he said, investigations were continuing. He did not comment on whether the use of pig swill was the trigger.
Pig swill from airports and ports cannot be fed to pigs in Ireland. Domestically produced swill is allowed into their food but only after careful processing.
The Department of Agriculture stressed that leftover food from aircraft and visiting vessels could not be incorporated into pig feed.
A Department spokesman said allowing such swill to be fed to pigs was banned in 1967, the last time foot-and-mouth became a big threat to Irish animals. "Swill from aircraft and from visiting ships is taken off and deep-buried under licence here," he said. A total of 31 Irish pig farms, however, are licensed to feed swill from hotels, food factories and other outlets in the Republic. "These operators are issued with a licence to feed domestic swill, but this material has to be heat-treated to a temperature which will kill any harmful diseases," he said.
Swill feeders are tightly supervised by Department inspectors to ensure they comply with regulations.
Initially scientists believed the British outbreak was caused when contaminated food from Asia arrived at Newcastle airport and was fed to pigs without being heat-treated.
Once infected, pigs can spread the disease rapidly as they can generate 100 million units of infected discharge into the air each day. Just 300 of such units can cause another animal to be infected.