Lab test confirmed that 23 tigers in a private zoo in eastern Thailand have died of infecting with avian influenza virus, officials said in Bangkok on Tuesday.

"All the 23 tigers have infected with H5N1 virus of bird flu," Charal Trinvuthipong, director of the Bird Flu Prevention and Elimination Center, told reporters.

The tigers might have infected with the virus for being fed with raw chicken in the Sri Racha Tiger Zoo, some 80 kilometers east of Bangkok, said Deputy Prime Minister Chaturon Chaisang.

Tigers in the private zoo started to show flu symptoms since last Thursday and altogether 23 have died until Tuesday.

Some 400 tigers kept by the private zoo are usually fed with raw chicken. Now, at least 30 tigers have fallen ill and more are feared to die of the disease, while the zoo has been closed.

Five tiger caretakers at the zoo also showed symptoms of flu and have been sent to hospital for medical examinations.

Earlier this year, a clouded leopard was infected with and diedof the poultry epidemic in eastern Thailand.

Having been hit by two rounds of bird flu outbreaks, the kingdom has suffered great economic loss including at least 30 million birds culled in the first outbreak and more than US$100 million have been spent for compensation.

The epidemic also claimed the lives of 11 Thais during the two outbreaks and the kingdom has been fully alerted over a "probable human-to-human transmission" case.

Describing tackling the disease as the country's top priority, Thai Prime Minister Thaksin Shinawatra earlier set Oct. 31 as the deadline to eradicate bird flu from Thailand.

The country is now undertaking a national campaign to switch open-field duck feeding to closed system so as to eradicate the disease.

Ducks raised in open fields are a crucial source of the H5N1 strain of bird flu and the poultry epidemic situation is feared to deteriorate in the coming cold season.

Ducks can carry the flu virus and they are strong enough to remain alive, and the virus can live in water sources for up to 30days.

The next step for the Thai government is to monitor fighting cocks and chickens raised at backyard.

In late September, the United Nations Food and Agriculture Organization (FAO) and the World Organization for Animal Health (OIE) jointly issued a statement, warning that the disease will not be eradicated from the region in the near future and asking for more investment to solve the problem.

(Xinhua News Agency October 20, 2004)