British authorities said on Tuesday they were investigating two new suspected cases of foot and mouth disease, raising fears that an existing outbreak of the livestock disease may not have been contained.
One of the suspected cases was in the southern English county of Kent, to the east of Surrey, where the highly infectious animal disease was found and hundreds of animals culled earlier this month, officials said.
The second suspected case was in Surrey, but outside the original disease area.
Authorities had hoped they had contained the outbreak in Surrey, and confirmation of new cases would be a blow to British agriculture.
The agriculture ministry said 3-km (2-mile) temporary control zones had been set up around a farm in Kent and unidentified premises in Surrey as precautionary measures following inconclusive assessments of clinical symptoms detected in farm animals.
Livestock movements are banned in the control zones.
Kevin Pearce, director of food and farming at the National Farmers' Union, said samples had been taken from animals at the Kent farm but no cull had been ordered.
It doesn't necessarily mean there is a case (of foot and mouth). It means that they have not been able to discount it straight away and as a precautionary measure they will be taking samples and testing for any signs of the virus, he said.
A national ban on animal movements has been in place since the confirmation on August 3 of foot and mouth in Surrey, although there are some exceptions such as the movement of animals to slaughter, to milking or for emergency treatment.
Britain's chief veterinary officer, Debby Reynolds, said on Monday she hoped to see an easing of the movement restrictions by the end of this week, but the suspected case in Kent could thwart that hope.
Reynolds said in a statement on Tuesday that this was a crucial week for vigilance on the outbreak.
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 in Kent, she said. At this stage disease has not been confirmed, laboratory results will follow.
More than 570 animals have been destroyed as a result of the outbreak and the European Union and other countries have banned British meat and dairy exports.
Farmers are frustrated by the movement ban and say the trade curbs are costing them 1.8 million pounds ($3.6 million) a day.
(Additional reporting by Sylvia Westall, Adrian Croft and Jeremy Lovell)