A "probable" new leak of foot and mouth disease has been discovered at the Merial Animal Health facility in Pirbright, Surrey, Environment Secretary Hilary Benn said today.
The virus is believed to have escaped through a leaking valve last week, but inspectors have been "assured" it has not been released into the environment, he added in a Commons written statement.
The Pirbright site, which also contains the Government's Institute for Animal Health, was the source of the foot and mouth outbreak in August.
The latest incident comes after the licence to use live viruses for vaccine production was restored to Merial on November 6 after the summer outbreak.
New measures were put in place to improve the drainage at the site, with both heat and chemical treatment to destroy live viruses.
But Mr Benn told MPs: "On Monday November 19 Merial discovered a shortfall in the quantity of virus recovered from production batches from the previous week.
"On inspection of the vaccine production equipment they identified possible technical problems with the functioning of a valve on a pipe leading from the centrifuge which is used to separate live virus from waste product."
He said operations were immediately stopped and citric acid was used to disinfect any virus which might have leaked from the centrifuge.
An engineer examined the machine on Tuesday morning and investigations focused on a valve separating the live virus product line from a line providing an outlet for condensation from a steam cleaner.
Mr Benn said safety measures require two operators to certify the valve is shut when the machine is used, and that the system is regularly inspected.
"Despite these measures Merial judged that the valve had been leaking, allowing an unintended probable release of live FMD virus into the contained drainage system, which was then pumped to the final chemical treatment facility without being heat treated," Mr Benn said.
On Tuesday Merial arranged for the valve to be replaced and tested the centrifuge to ensure it was now working properly.
The Department for Environment, Food and Rural Affairs has suspended Merial's licence and an inspection team visited the site yesterday morning.
"The inspection team judge that while it was possible that live FMD virus had entered the contained drainage system, from their discussions and the evidence gathered they are assured that live virus has not been released to the environment," Mr Benn said.
Biosecurity measures required under the licence "effectively contained the virus in the closed, re-lined drainage system before deactivation in the chemical treatment facility", he added.
Merial's licence will remain suspended while inspectors produce a full report.
Farming Minister Lord Rooker today insisted that there had been no escape of the disease from the Pirbright site and said there was no cause for panic.
"There's been no escape of foot and mouth; something happened in the production process which was reported to us on Tuesday and full engineering work was done yesterday."
He added that the virus had only gone into the new drainage system and was picked up by checks on the first week of new production of the vaccine.
Lord Rooker added that the ministerial statement had been released because of the sensitivity surrounding Merial.Reuse content