Bird flu has killed poultry in a seventh province in southern Vietnam, state media said, describing the spread of the disease across the Mekong Delta as alarming.

More than 130 ducks died of the virus in Soc Trang province in recent days, government-run television reported, hours after officials said over 800 ducks had also died of the H5N1 bird flu strain in Tra Vinh province.

"The bird flu situation is becoming more and more complicated and alarming in the Mekong Delta," the state television report said, quoting a Ministry of Agriculture statement Sunday.

Vietnam has reported no new human cases since November 2005 of the disease that killed 42 people in the country between 2003 and 2005, but a new wave of outbreaks, mostly on small poultry farms, started in December.

The World Health Organisation, the UN Food and Agriculture Organisation and the Vietnamese government last week dispatched an expert team to the region to assess the situation.

Vietnamese animal health workers have slaughtered thousands of ducks and chickens and vaccinated nearly two million animals in recent weeks in an effort to contain the latest series of outbreaks, the Vietnam News Agency reported.

Bird flu has now struck scores of poultry farms in the southern provinces of Ca Mau, Bac Lieu, Hau Giang, Kien Giang, Vinh Long, Tra Vinh and Soc Trang provinces, the Ministry of Agriculture said.

Health experts warn that the bird flu risk, like that of other respiratory ailments, increases in the winter months and around the mid-February Tet New Year festival, when poultry consumption and the movement of people rises.

The global death toll from bird flu since 2003 stands at 161, but epidemiologists fear bird flu could trigger a global pandemic if it were to mutate and become easily transmitted between humans.