Cattle culled at a second Surrey farm have tested positive for foot-and-mouth disease, it has been confirmed.
A 10km (6.2 miles) control zone is in place around the affected farms
The "precautionary" cull of animals had taken place at Stroude Farm, Egham, near the scene of the outbreak of the disease discovered on Wednesday.
Initial tests say the strain found on Wednesday was the same as that found during the outbreak in August.
The government is being urged to ease movement restrictions on some animals in England, as in Scotland and Wales.
Debby Reynolds, the government's chief vet, confirmed that foot-and-mouth had been present at the farm - taking the total number of farms where the disease has been found in 2007 to four.
Dr Reynolds said she was glad that all the animals on the farm had been culled before the test results were announced.
Stroude farm is about 10 miles from the Pirbright research complex - blamed as the source for the foot-and-mouth outbreaks at two farms last month.
Environment department sources say a total of 940 cattle and pigs have been culled so far in the latest outbreak.
The two farming businesses affected - Stroude Farm and Hardwick Park Farm where the first case was identified on Wednesday - are spread over eight areas including Ripley, Shepperton, Staines and Thorpe.
A 3km (1.8-mile) protection zone has been set up around the farming land, with a 10km (6.2-mile) surveillance zone encircling it.
Culling is expected to be finished by Friday night, with cordons due to be lifted by Saturday morning.
Scientists investigating the disease are working on the possibility it was carried by soil or through the air, and was not a water-borne transmission.
The movement ban was put in place across Britain when cattle on land in Egham were found to be infected on Wednesday.
WHAT CONTROL ZONE MEANS
Protection zone (3km) - all premises containing livestock inspected by vets, and subject to restrictions on movements of animals, animal products, some vehicles, and some activities
Surveillance zone (10km) - restrictions on movements of susceptible animals, animal products, manure, and some activities. No restrictions on the movement of non-susceptible animals such as pets, vehicles, or slaughter for private consumption
Administrations in Wales and Scotland eased the restrictions to allow farmers to take livestock direct to slaughter.
Animals can still not be traded or moved for any other reason. The Welsh Rural Affairs Minister Elin Jones said the decision was a "proportionate" response.
The restrictions have been questioned by some. One Northumberland farmer, 300 miles from the Surrey outbreak, asked why he could not move his lambs to slaughter.
"Welsh farmers, who may be situated less than 100 miles from the outbreak, could do this. How can this be on the basis of good scientific evidence?" David Renner told BBC News.
Farmers said the latest outbreak was "much worse" than last month's, because it had come at a time when livestock farmers needed to move their animals, and send them to market.
National Farmers' Union president Peter Kendall said the restrictions would have "enormous economic consequences" for the already struggling livestock industry.
Prince Charles, patron of the Farm Crisis Network, had to cancel a planned visit to North Yorkshire farmers because of movement restrictions.
"For all the poor farmers, particularly all the livestock ones, it's a complete nightmare to have another outbreak, and everything brought to a grinding halt, particularly at a time when all the autumn sheep sales are coming up.
"It is a real real blow for people."
The disease was confirmed in Egham only a week after the previous restrictions on cattle movements were lifted.
WHY IS THE VIRUS BACK?
The foot-and-mouth virus is less symptomatic in sheep so an infection from the first outbreak could have been overlooked
The virus can survive in soil for up to 28 days
It can also survive in water for up to 50 days
Foot-and-mouth can also linger in hay and straw for up to 20 weeks
It could be a new strain of the virus, but experts say this is unlikely
The government is facing criticism that it was too quick to declare Britain foot-and-mouth free last week.
It has denied that Dr Reynolds was pressurised into giving the all-clear too early after the last outbreak.
But shadow environment secretary Peter Ainsworth said the matter "does raise further questions about why the government felt able to declare that foot-and-mouth disease had been 'eradicated'. This was clearly a tragic misjudgement".
The European Commission has banned all live animals susceptible to foot-and-mouth from being exported from Britain. Northern Ireland is exempt from the ban, and can export freely.
Do you live near the site of the suspected outbreak? Do you have any information that you would like to share? Send us your comments by filling in the form below.
The BBC may edit your comments and not all emails will be published. Your comments may be published on any BBC media worldwide.