An official report into two outbreaks of foot and mouth disease in Britain found there was a 'strong probability' that the virus came from a nearby research centre.
But the eagerly-awaited report did not point the finger at either a government-run laboratory or private vaccine company Merial that share the Pirbright site.
The inspectors said there was a real possibility that human movement was responsible for releasing the virus, although it did not go into detail.
The report also said there was a negligible likelihood that the virus had been dispersed from the research laboratories on the air.
Instead, it said that waterborne release onto the site of infection remains a possibility.
Earlier, the Minister for Agriculture, Mary Coughlan, has said no further measures, other than those adopted by the European Commission, are required at this time in response to the foot and mouth outbreak.
The Minister had been meeting with senior Department of Agriculture officials to discuss the implications of the outbreak in the UK.
Minister Coughlan said the confirmation of a second case of foot and mouth disease in Surrey was disappointing but not surprising, given its proximity to the first case.
Ms Coughlan said that she and her officials were being kept fully up-to-date on emerging developments and were continuing to closely monitor the situation.
In compliance with the EU Commission decision, a complete ban was being maintained on the importation from Britain of cattle, sheep, pigs and goats, meat and meat products, milk and dairy products and some other animal products.
Minister Coughlan has also issued an order requiring disinfecting of vehicles used for transporting animals by slaughter houses as well as at ports and harbours.
With regard to Northern Ireland, which is not included in the ban, a system of certification will apply in relation to the importation of live animals, meat and meat products, milk and dairy products as well as other animal products.
Meanwhile, Northern Ireland's First Minister, Ian Paisley, has been in contact with the British Foreign Office after NI firms reported difficulties shipping meat and dairy products to some countries.
Northern Ireland is exempt from an EU ban on British exports of meat and dairy products. However, a shipment of pork from Co Tyrone was stopped from entering Japan and a local dairy company claimed Germany had refused its produce.
IFA President Padraig Walshe has said he hopes the export of Irish meat and diary products will not be affected by the continuing scare in Britain.
Sewer overflowed at infected site
The farmer at the centre of the UK foot and mouth outbreak said today his family was devastated.
At a news conference in Guildford, Roger Pride, who runs Woolford's farm near Godalming in Surrey with his wife Valerie, said they were victims of circumstances beyond their control.
He said a sewer overflowed into a field where the cattle were grazing.
Mr Pride, son of farm owner Derrick Pride, said nobody from the farm had any contact with either of the labs suspected of spreading the virus.
He also revealed that the animals had not been moved since early June.
Test results overnight confirmed a second outbreak of foot and mouth disease on a farm near the original infection site in Surrey.
UK Environment Secretary Hillary Benn confirmed this morning that animals culled on the second farm had been infected.
After the initial outbreak, near the village of Normandy in Surrey, some 120 cattle were slaughtered. Three have so far found to be infected with foot and mouth.
Experts ordered a further 50 cattle to be culled on the second farm, which is also in the 3km protection zone around the first outbreak.
Investigations into the source of the first outbreak have centred on the nearby Pirbright research centre, after tests found that the virus involved was similar to one made there.
The type of virus in the second outbreak was not immediately confirmed.
