The Health and Safety Executive (HSE) said today construction work around the Pirbright animal health site was responsible for spreading the virus to nearby farms.

HSE chief executive Geoffrey Podger saidwaste water containing the virus leaked out of cracked pipes and contaminated the surrounding soil. He said the virus spread because human and vehicle movements were not adequately controlled.

Podger said: “In particular, vehicles associated with ongoing construction work had relatively unrestricted access to the site. In our opinion, these construction activities - very near to the effluent drainage system - are likely to have caused disturbance and movement of soil in a way that contaminated some of the vehicles with the live virus. We established that some of the vehicles, probably contaminated, drove from the site along a road that passes the first infected farm. We conclude therefore that this combination of events is the likely link between the release of the live virus from Pirbright and the first outbreak of foot and mouth disease.”