Investigators have determined a pipe at a research laboratory facility in southern England caused last month’s outbreak of foot-and-mouth disease (FMD), the British Broadcasting Corp. reported Wednesday.

Britain’s Health and Safety Executive found there were biosecurity lapses at the facility in Pirbright, Surrey, the BBC reported. The investigators’ official report is due to be published Friday.

The Environment Department would not comment on the report Wednesday.

The lab complex houses vaccine-maker Merial Animal Health–the British arm of U.S.-French pharmaceutical firm Merial Ltd.–and the government’s Institute of Animal Health.

Virus traces were found in a pipe running from Merial’s lab to a treatment plant operated by the government-run lab, the BBC reported, adding the pipe might have been damaged by tree roots.

Investigators found contractors working at Pirbright travelled to and from the site using a country road next to the farm where the first outbreak occurred, the BBC said.

Foot-and-mouth disease affects cloven-hoofed animals including cows, sheep, pigs, and goats. Horses cannot be infected by FMD, but can carry the virus on their hooves, skin, hair, and possibly in their nasal passages.

It does not typically infect humans, but its appearance among farm animals can have a far-reaching economic impact.

After the outbreak was detected on Aug. 3, Britain suspended exports of livestock, meat, and milk products for nearly three weeks. About 600 animals were slaughtered as a result of the outbreak.

Although several sites were tested, only two farms–both about 30 miles southwest of London–had cattle confirmed with the disease.