Britain on Thursday announced the discovery of a highly contagious strain of bird flu in a wild duck found dead in Wales, warning poultry keepers to remain vigilant as Christmas approaches.

The same H5N8 strain was detected last week at a turkey farm in Lincolnshire in eastern England but the government said there was no suggestion the disease had spread from that farm to the duck.

"As this is a wild bird, it highlights the importance for poultry keepers to follow our clear advice on biosecurity," the government's chief veterinary officer Nigel Gibbens said in a statement.

Gibbens said the risk to was "very low".

The H5N8 strain can spread quickly in affected farms and can lead to the culling of thousands of birds.

The strain has been detected in 13 other European countries including France and Germany since October.

Hungary is the country that has had the highest number of outbreaks in that time, with 201 instances reported on farms and four in wild birds.