Britain's Health and Safety Executive has revealed that bio-terrorists may be responsible for the spread of foot and mouth from an animal health laboratory.
The virus could have been deliberately leaked from a hi-tech complex at Pirbright, Surrey, the Daily Express quoted officials, as saying.
It follows an investigation launched after the disease was discovered in cattle on a farm less the three miles away from the site. The report, however, rules out airborne transmission as a possible way in which the virus spread, and an alternative theory that it was carried in water, was seen as negligible.
Crucially, officials could not say whether the leak was accidental or deliberate.
Britain's Environment Secretary Hilary Benn has announced a further probe into the human link as a "matter of urgency".
The report confirms the Pirbright site as the most likely source of the infection, but fails to establish from which of two laboratories it originated.
The complex houses the Government-funded Institute for Animal Health and the privately run Merial Animal Health. Both have previously denied they are responsible for the leak.
The Health and Safety Executive has recommended that Merial's work be restricted.
It throws into question whether the company can begin production of vaccines for the Government.
Earlier this week Debby Reynolds, the chief veterinary officer, ordered 300,000 doses of the strain of foot and mouth found on the two farms, which has been kept since the epidemic that spread Britain in 1967.