The British Health and Safety Executive said there was a “real possibility” the disease was spread by human movement, and the chances it was caused by flooding or aerial transmission were “negligible”.
But the executive’s investigations failed to pinpoint the source as either the private Merial Animal Health Ltd, part of the site near Guildford, Surrey, or as that of the Government-run diagnostic and research centre, the Institute for Animal Health.
Both organisations at the site use the strain of the virus detected in the slaughtered cattle, but have insisted there is no evidence of biosecurity breaches at their labs.
In a statement Merial, whose work includes manufacturing vaccines, said: “Following the announcement of the independent report’s finding, Merial is assessing the information contained. We will communicate further as soon as possible.”
Yesterday, Minister for Agriculture Mary Coughlan said the confirmation of a second case of foot and mouth disease in Surrey was disappointing but not surprising, given its proximity to the first case.
The second case had involved livestock owned by farmer John Gunner, while Roger Pride, whose cattle are at the centre of the original outbreak, spoke of his “devastation” at finding foot and mouth in his herd.
Describing the moment when his suspicions were confirmed last Friday, he said in a statement: “It felt as if our whole world was turned upside down.”
Mr Pride, who runs Woolford Farm at Elstead near Guildford with his wife Valerie, added: “Whatever the cause of the outbreak, it is obvious we have been the victims of circumstances far beyond our control.”
He suggested that recent flooding could also be behind the outbreak.
“The theory that the sewer which overflows into part of the field where the 38 [infected] cattle were grazing could be the cause is an obvious possibility. Certainly no one at the farm has had contact with the Pirbright facility,” he said.
Police were guarding the gates of Mr Gunner’s house in the village of Wood Street, near Guildford, last evening. The farmer’s wife, who refused to give her name, said of the news that the herd would be culled: “It is as bad as it gets.”
Measures by Britain’s Department for Environment, Food and Rural Affairs include slaughtering cattle on three sites at the first farm and setting up protection and surveillance zones.
Susceptible animals on an adjacent farm were also culled because of “potentially dangerous contact”.
It emerged last night that there was a five-day gap between the farmer on the first farm noticing signs of illness in his animals and the authorities being notified.
Meanwhile, the North’s food export woes grew yesterday after another company said its products had been turned away despite exemption from the EU ban on British meat exports.
Dairy produce from Belfast-based Dale Farm was shunned in Germany and a shipment of pork was rejected by Japan, despite the Brussels go-ahead to sell on the world market.
Stormont First Minister Ian Paisley was in urgent talks with the Japanese ambassador in London.
Dale Farm is also experiencing difficulties with supplies to South America.
Tyrone pork processors Grampian Food, which also has deliveries to Germany and the US, called a halt to exports until the situation is resolved.