Istanbul, Turkey ? The slaughter of thousands of domestic fowl in Turkey and Romania began Sunday as a precaution against the spread of bird flu after both countries confirmed their first cases of the disease over the weekend.

In western Turkey, military police set up roadblocks at the entrance to a village near Balikesir. A two-mile radius was quarantined as veterinarians and other officials began destroying poultry at two turkey farms.

It was not clear how many animals would be destroyed, but the Anatolia news agency reported that authorities had slaughtered 600 out of 2,500 turkeys on one farm by noon Sunday.

Other fowl – including pigeons – and stray dogs in the village would also be killed as a precaution, said Nihat Pakdil, undersecretary of Turkey’s Agriculture Ministry.

Bird flu was detected at a turkey farm after some 1,800 birds died this week, the Anatolia news agency reported. All animals in the farm were destroyed.

Turkey’s Agriculture Ministry confirmed the outbreak Saturday and said the disease was believed to have spread from migratory birds on their way to Africa from Russia’s Ural mountains.

Scientists have apparently narrowed the disease in Turkey down to an H5 type virus – the family of the bird flu virus that experts fear could be the source of a potential global pandemic among humans – but have not narrowed it further to determine whether it is the H5N1 strain that health officials are particularly worried about.

Cases of bird flu were also confirmed Saturday in Romania, where a total of 40,000 birds were expected to be slaughtered as a precaution. Authorities there said no new cases of bird flu had been confirmed yet.

On Friday, Romanian authorities reported the country’s first suspected bird flu cases – three domestic ducks that died of bird flu in the Ceamurlia village in eastern Romania.

On Saturday, a dead swan found on a beach in the Black Sea port of Constanta similarly tested positive for bird flu antibodies.

Tests in Britain will determine whether the disease, which infected fowl in the Danube River Delta, is the H5N1 strain.

H5N1 has swept through poultry populations in Asia since 2003, infecting humans and killing at least 60 people, mostly poultry workers, and resulting in the deaths of more than 100 million birds. The virus does not pass from person to person easily, but experts believe it could mutate to a form that becomes a human flu virus, passing easily between people and triggering a pandemic.