Officials, meanwhile, have confirmed that a third farm being tested for the virus, 12 miles from the outbreak in Surrey, is free of the disease.

The stream involved runs past an allotment used by a senior employee of the pharmaceutical company linked to the outbreak, before passing through nearby fields used by the two farms hit by the virus.

Merial UK, which shares the Pirbright high-security laboratory site with the government-funded Institute for Animal Health, also admitted that blue chemical barrels scattered on the allotment had not been decontaminated before being taken off the site.

Source: Sunday Telegraph