Bluetongue was first reported in the UK in 2007
Two cases of animal disease bluetongue have been detected in imported rams, the Department for Environment, Food and Rural Affairs (Defra) has said.
The rams were imported from the same premises in the bluetongue-restricted zone in France.
The cases were found on premises near Lewes, East Sussex, and Hemel Hempstead, Hertfordshire.
Defra said there was no evidence the disease was being circulated by midges in the areas where cases were found.
The cases were detected as a result of post-import testing on all animals coming from the Continent which are susceptible to the disease, according to Defra.
Bluetongue, which can be fatal to animals, is transmitted between animals such as cows and sheep by midges.
Farmers throughout the protection zone should vaccinate as soon as vaccine is available to them
Deputy chief vet
The first outbreak of the disease in the UK hit the country in summer 2007.
A mass vaccination campaign against the disease began in April.
Some 21.5 million doses of vaccine have been made available to farmers.
Deputy Chief Vet Alick Simmons said the disease "has recently been confirmed as circulating this year in the Netherlands and large areas of France, despite vaccination programmes being undertaken".
"Similar re-emergence of the disease in the UK would also not be unexpected in the coming weeks," he said.
The bluetongue protection zone, which has kept in place to allow for vaccination, covers most of England.
It is legally permissible to import animals from France's protection zone.
Mr Simmons said the latest cases emphasised the need for farmers to be aware of the risks of importing animals from within restricted zones and the importance of vaccination.
"Farmers throughout the protection zone should vaccinate as soon as vaccine is available to them," he said.