The European Union supports the UK’s self-imposed ban on exports.
The latest outbreak has brought back memories of 2001, when more than six million animals had to slaughtered costing the agriculture and rural tourism industries an estimated $17bn.
“We were starting to think this virus had been contained and maybe we were going to be getting back to normality in a few weeks,” Laurence Matthews, who owns the farm where the second infected herd grazed, said on Tuesday.
“Now this has set us back again and most farmers, and I’ve been speaking to a few, are very, very scared.”
The outbreaks come amid widespread flooding, and investigators have been considering the possibility that the flooding might have helped spread the virus.
The strain had not been seen in animals for a long time but was used to produce vaccines, she said.
Biosecurity experts are focusing on two laboratories as the possible source of the outbreak.
The government-run Institute for Animal Health and a facility operated by Merial Animal Health, a US-French company, both handle foot-and-mouth virus samples.
|Investigators are looking at whether flooding
may have spread the virus [EPA]
Both have stocks of the uncommon strain of foot and mouth that was found to have infected the first herd of cattle.
Merial made a batch of vaccines containing that strain of the virus last month.
Both laboratories have since issued statements denying there was any breach of their biosecurity measures.
Government inspectors are expected to issue a report of their findings on Tuesday after conducting a search of both laboratories.
A nationwide ban on all livestock movement is expected to last for several weeks at least, raising concerns of a deep economic impact on the meat farming industry that is worth more than $1bn a year.
The European Union has endorsed Britain‘s decision to ban meat and dairy exports.