The deliberate release of viral material, possibly in an act of sabotage, may have caused the foot-and-mouth disease outbreak, officials said last night. The Health and Safety Executive (HSE) said in a report ordered by the Prime Minister that “release by human movement [of the FMD virus] must be considered a real possibility”. Inspectors all but discounted theories that the virus escaped by air or water from the laboratory complex close to where the outbreak started, although they are continuing to investigate the possibility of equipment failure or a security breach.