Foot and mouth disease has been confirmed on a second farm west of London, near a renewed outbreak earlier this week.
Britain's Department for Environment, Food & Rural Affairs said cattle culled on a farm near Egham in Surrey had tested positive for the disease.
The farm is within the existing protection zone and adjacent to the previously infected premises.
A first new case was confirmed in the area on Wednesday, a week after the government had declared the country free of the disease following an outbreak in August. That outbreak has been blamed on a nearby research laboratory.
