A three-kilometre (1.8-mile) temporary control zone has been imposed around premises close to the town of Rye, near the southern English coast, after sheep showed possible symptoms of the disease. Tests were being carried out.
The zone, in the county of Sussex, is about 65 miles (100 kilometres) from where the first outbreak this year was confirmed on August 3 in the county of Surrey, south-west of London.
If confirmed, it would be the ninth premises on which foot and mouth has broken out -- and worryingly the first outside Surrey.
The temporary control zone includes the country home of Beatles pop legend Paul McCartney, though it does not centre on the estate.
Laboratory tests were being carried out to determine whether the disease has spread, but there is no timetable for receiving the results, said a spokesman from the Department for Environment, Food and Rural Affairs (Defra).
"Animal keepers are urged to remain vigilant for disease, check their animals twice a day and report any suspicions immediately," he added.
All animal movement restrictions imposed in England following the confirmed outbreaks of foot and mouth are to be lifted on Wednesday, along with the three-kilometre protection zone in Surrey.
But a wider 10-kilometre surveillance zone in the county is set to remain in place until at least November 5, although its size is being kept under constant review, Defra said Friday.
The lifting of restrictions is conditional on no new foot and mouth cases being confirmed, the ministry added.
Since August 3, about 1,800 animals have been culled, some as a precaution.
British farmers are also having to deal with an outbreak of bluetongue disease in cattle and sheep.
Foot and mouth last appeared in Britain in 2001 and spread rapidly across the country, ravaging the farming and tourism sectors.