Investigations into how the epidemic began have concluded that the disease in England spread from Burnside pig farm in Heddon-on-the-wall, Northumberland.

The key aspect now is that a strong system of controls are in place to detect at the earliest opportunity any potential threats in the future

National Farmers' Union

Contaminated meat was probably the source of the infections on that farm, says the Department of Environment, Food and Rural Affairs report on Thursday.

But it adds: "It is unlikely that the origin of this material and the route by which it entered the UK will ever be identified."

'Keeping quiet'

That may be a worrying sign for future efforts to stop disease entering the country in future, although the crisis has prompted renewed scrutiny of meat imports.

Bobby Waugh, the Burnside farmer, was last month found guilty of keeping quiet about an outbreak of the disease among his livestock at the start of last year's crisis.

Waugh was found guilty of nine animal health and cruelty charges.

Bobby Waugh was found to have kept quiet on the outbreak

The report also revealed that a raid on a warehouse in Northumberland discovered illegally imported meat from China or Hong Kong.

That has not been specifically linked to the outbreak but vets believe the UK strain foot-and-mouth originated in the Far East.

There is no suggestion Waugh was connected to the warehouse where meat imports were found.

Illegal imports

However, the report says the infected meat to blame for last year's crisis was probably illegally imported.

Such illegal shipments were likely to have been intended for wholesale outlets, or for sale to restaurants and canteens, it suggests.

Since the epidemic, a total ban has been imposed on feeding catering waste to livestock - one of Mr Waugh's convictions was for feeding unprocessed waste to his animals.

Diseased pigs helped spread the disease

The report said there were two routes in which the disease spread from the Heddon-on-the-wall farm.

Diseased pigs were moved to other farms in Essex and Kent, and the wind carried the virus to sheep onto a neighbouring farm.

Those sheep were then sold through markets in northern England, spreading the disease further.

Controls in place

The National Farmer's Union said it would have been extremely valuable to have been able to trace right back to the original source of the infection.

But an NFU spokeswoman told BBC News Online: "The key aspect now is that a strong system of controls are in place to detect at the earliest opportunity any potential threats in the future."

Conservative shadow rural affairs secretary David Lidington said ministers had set out how they would prevent on illegal imports.

"But there has been precious little action to date and even less sense of urgency," he said.

"The sad fact is that the disease could be imported into the country again tomorrow."