From midnight on Saturday, animals outside the surveillance zone set up around two farms in Egham, Surrey, were allowed to be moved to slaughter, under strict biosecurity conditions.
However, the government has urged farmers to remain vigilant after pigs on a farm in close proximity to the two infected sites in Surrey were slaughtered as a precaution. Veterinary inspection for clinical signs of the virus were inconclusive, said chief veterinary officer Debby Reynolds.
The latest outbreak has so far been contained to two sites although reports in The Times suggest a third case on a plot of land near Chertsey, Surrey, could be confirmed by Defra later today.
Meanwhile, test results confirmed over the weekend that the virus found at the two sites was the same 01 BFS 67 strain as the original outbreak at two farms in Pirbright, Surrey, last month.
Scientists are continuing to investigate how the disease has re-emerged just days after the government declared the UK foot and mouth free.