British health authorities say tests on the deadly H5N1 strains of bird flu virus found recently in Britain and Hungary show they are essentially identical.
However, British veterinarians investigating the case say there is no evidence yet of either the illegal or unsafe movement of poultry products between the two countries.
In Budapest Tuesday, animal health authorities said no live birds or eggs have been exported to Britain or elsewhere since the virus was detected in southeastern Hungary in January. Officials say the last exports from the infected region occured in November of 2006.
As the European probe continues, Vietnam says its most recent bird flu outbreak has been contained.
Vietnam has had no human cases of bird flu since late 2005, but the virus re-emerged on poultry farms in the Mekong Delta in December.
With 42 deaths, Vietnam is second only to Indonesia in the number of human fatalities from bird flu.
The H5N1 strain has killed more than 160 people worldwide since 2003, most of them in Asia. Experts fear the virus could mutate into a form easily passed from human to human.
Some information for this report was provided by AFP, AP and Reuters.
