Tests on livestock for foot and mouth disease at a fourth farm in southern England have proved negative, the British government said on Saturday, easing fears the highly infectious virus had spread.
Inspectors cleared animals of foot and mouth on the Surrey farm about 12 miles (19 km) east of a surveillance zone where two farms have tested positive, said the farm and environment ministry Defra.
Temporary controls around the property were lifted. Tests on a third farm in the area for the disease, which devastated British farming in 2001, have also proved negative.
"It's early days but so far our evaluation is that the risk of spread outside the zone in Surrey is low," chief veterinary officer Debby Reynolds told BBC Television.
But she added: "It is day eight ... relentless vigilance amongst the farming community is the order of the day."
As a result of the outbreak, more than 570 animals have been destroyed and the European Union and individual countries have banned British meat and dairy exports.
Farmers say the trade curbs are costing them 1.8 million pounds ($3.6 million) a day.
A severe outbreak of foot and mouth disease in 2001 forced the slaughter of six million animals and inflicted billions of dollars of losses on farmers and the tourism industry as much of the countryside was closed to visitors.
Reynolds said a research facility at Pirbright in Surrey that was developing foot and mouth vaccine was the probable source of the outbreak but an investigation continued.
She declined to comment on whether police were involved in the inquiry but, asked whether deliberate contamination was being considered, she said: "Every avenue of investigation is going on, to piece together all of the bits of the jigsaw."
BOOST FOR BROWN
The Pirbright facility houses a government-run laboratory and a second lab Merial, owned by U.S. firm Merck and French firm Sanofi-Aventis SA.
Both labs say they adhere to strict hygiene measures. Inspectors have interviewed staff and visited a nearby vegetable garden owned by a Merial executive.
Foot and mouth spreads easily on the wind and causes animals to foam at the mouth and collapse.
A national ban on the movement of livestock remains in place but was eased on Thursday to permit farmers outside the infected area to move animals to slaughter.
Other countryside activities, such as taking animals to farmers' markets, have been curtailed.
The outbreak is the latest in a run of crises, including devastating floods and attempted car bombs, to hit Gordon Brown in his first weeks as prime minister but a poll on Saturday showed the public approved of his responses so far.
In an Ipsos Mori poll in The Sun newspaper, 69 percent of people said Brown was the best leader for Britain in crisis situations, against 10 percent who said they would rather see opposition Conservative Party leader David Cameron in charge.
The poll gave Labour a five-point lead over the Conservatives, with Labour down one point since June at 38 percent and the Conservatives down three at 33 percent.
