Romanian officials say four new cases of a deadly strain of avian flu have been found in birds in a remote village in the Danube River delta.

Romania's agriculture minister, Gheorghe Flutur, said British lab tests confirm four dead chickens in the village of Caraorman carried the H5N1 strain of the virus that has killed more than 60 people in Asia since 2003.

China's Agriculture Ministry also confirmed Monday that bird flu was the cause of illness among chickens, ducks, and geese last week in the Inner Mongolia Autonomous Region and central China's Hubei province.

On Sunday, U.S. Health and Human Services Secretary Mike Leavitt said it would take the United States at least three to five years to produce 300 million doses of a vaccine to protect Americans from a possible pandemic.