Hundreds of ducks in Vietnam's central highland Lam Dong province have died with unidentified causes, Vietnam News Agency reported Thursday.

The ducks in a farm in Duc Trong district have died with symptoms of head and eye oedema, and diarrhea. Local veterinary agency has slaughtered all the flock of 4,000 ducks to prevent bird flu.

The disease is likely to return Vietnam in October when weather conditions favor the development of bird flu viruses, according to the Department of Animal Health under the country's Ministry of Agriculture and Rural Development.

Bird flu outbreaks, starting in Vietnam in December 2003, have killed and led to the forced culling of dozens of millions of fowls. The last outbreak of bird flu among poultry in the country was in December 2005, according to the ministry.

Source: Xinhua