It followed an "inconclusive assessment" of symptoms in cattle.
Chief Veterinary Officer Debby Reynolds said: "This is a developing disease situation. The containment and eradication of foot and mouth disease remains our priority. This is why we have moved swiftly to put in place a temporary control zone while we investigate this development. At this stage disease has not been confirmed, laboratory results will follow."
The new zone is to the west of Dorking and close to the two confirmed cases of the disease.