* EU executive reports Romanian H5N1 flu outbreak
* Romania confirms, awaits UK laboratory tests
* Exclusion zone enforced across 20 km
* Wild bird migration routes could spread virus
(Adds Romanian comment, background)
By Pete Harrison and Radu Marinas
BRUSSELS/BUCHAREST, March 16 (Reuters) - Romania has identified an outbreak of bird flu at a poultry farm close to Ukraine and enforced a 20 km-wide surveillance zone around it, the European Union's executive said on Tuesday.
The outbreak of the H5N1 virus in the commune of Letea near the Ukrainian border is on a key migratory pathway for wild birds, which could aid its spread.
"Romania's national laboratory confirmed yesterday that the outbreak concerns the highly pathogenic H5N1 strain of avian influenza," the European Commission said in a statement.
"In order to limit the spread of the virus, the Romanian authorities applied immediately the necessary control measures," it added.
While scarce media attention has been paid in the last year to H5N1, there have been outbreaks of the disease in birds and it has killed people in China, Egypt, Indonesia and Vietnam.
This is the first case detected in Europe since it was found in a wild duck in Germany a year ago.
Even though H5N1 transmission between people is weak, experts say it is still a risk, especially if it mixes with the now dominant H1N1 swine flu virus. Such a hybrid may then be deadly and more easily transmitted among people.
All birds in the farm have been slaughtered and now a 6 km-wide protection zone must be enforced around it, surrounded by a 20 km-wide "high risk" surveillance zone with strict movement controls.
"British tests to confirm the disease are under way at the reference laboratory in Britain," Marian Zlotea, head of Romania's national sanitary-veterinary authority, told Reuters.
"We are talking about a very small peasant farm, situated in a very isolated area ... and two hens. Probably the strain has been brought by migratory birds," Zlotea added.
Romania's geography increases the risk of the virus spreading. It lies on the Via Pontica migratory route, which wild birds use to fly north from Africa to Scandinavia and Siberia in the spring.
Romania was the first country in Europe to detect the H5N1 virus in September 2005 and a year later it contained the disease. By then it had spread from Asia across Europe, the Middle East and Africa.
Last month, a Vietnamese poultry worker died from bird flu, the country's first fatality from the virus this year. Vietnam has confirmed 114 human H5N1 infections since 2003, 58 of them fatal. (Editing by Dale Hudson and Anthony Barker)