Bluetongue virus has been detected in 20 imported cows on premises near Worcester, DEFRA has confirmed.

The farm is within the current bluetongue surveillance zone.

The animals originated from within a Protection Zone in the Netherlands, and were detected through DEFRA's routine post-import testing carried out on all bluetongue susceptible animals entering the UK.

DEFRA is also investigating why the presence of bluetongue was not detected in the pre-movement testing and veterinary inspection required under EU law.

The farm near Worcester has been placed under restrictions, and the animals will be culled as they potentially provide a source of infection for the local midge population, and therefore other animals.

Currently there is no evidence that virus is circulating in the area, therefore there will be no changes to the existing Bluetongue zones and no new zones will be established at this time. This decision will be kept under review pending a full epidemiological investigation being undertaken on the premises.

Acting Chief Veterinary Officer Fred Landeg reminded all producers considering importing animals from a diseased area of the need to be vigilant.

"As with the case of bluetongue found in an imported animal in Middlesbrough last week, this re-emphasises the importance of livestock keepers carefully considering the potential risks to UK industry as a whole from importing animals from bluetongue restricted zones."

On hearing the news the NFU called on government to ban imports of livestock from the bluetongue areas of Northern Europe, but it remains uncertain as to how this could be done without contravening EU law.

According to the NFU the cattle were not tested before being exported to the UK and the importer failed to inform DEFAR of the consignment, with the result that the animals were not tested on entry.

An NFU spokesman said that even though the law had clearly been broken, the incident had exposed a loophole in the UK's disease precautions.

"This is the second time in a week that animals infected with bluetongue have been imported. Until such time as arrangements are in place to prevent this sort of thing happening, the only safe course of action is to ban all imports of livestock from the bluetongue infected areas.

"British livestock farmers have put up with huge disruption and inconvenience in order to contain the disease and so make it more likely that it can be eliminated quickly and completely once a vaccine becomes available.

"We cannot allow our sacrifice to be undermined by disease being spread far and wide by infected animals imported from abroad."