Three more tigers died of bird flu at a private zoo in eastern Thailand, raising the total number of the big cats killed by the epidemic to 63, local press reported Friday in Bangkok.

The latest tiger deaths were disclosed Thursday by Somchuan Rattanamungklanondh, a veterinarian at the Animals Research and Development Center for the Eastern Region.

By far, a total of 63 tiger at Sri Racha Tiger Zoo have succumbed to bird flu, including 30 put down Wednesday to prevent the spread of the disease.

The remaining 378 tigers had been infected with Tamiful, developed by Swiss Hoffmann-La Roche company and Gilead Sciences of America, to fight the virus. Among them, 25 suspected to be infected have been put under surveillance.

Lab test showed that the avian influenza virus that killed the big cats at the Zoo had not mutated, Dr Charal Trinvuthipong, director of the government's bird-flu center was quoted by newspaper The Nation as saying.

The 57 zoo keepers who were proved free of the disease have been asked to stay at home and gone through daily physical check-ups.

Charal dismissed reports that crocodiles at the Samut Rrakan Crocodile Farm and Zoo had perished from bird flu, saying reptiles were not susceptible to the avian virus, and only mammal such as dogs and cats could be affected.

The provincial committee fighting bird flu on Thursday questioned Somjit sae Seow, believed to be the middleman who supplied raw chicken fed to the big cats at the zoo, to identify the origin of the chicken, but no detail came out of the meeting.

Meanwhile, 170 fighting cocks at a farm in Trat's Khao Saming district were waiting to be culled after in a test showing they could be infected with bird flu.

If avian flu infection is confirmed, anti-bird flu measures will be carried out with a five-kilometer radius including a ban on poultry movement, culling and sterilization.

Pending the expire of one-month deadline for ending the epidemic,Prime Minister Thaksin Shinawatra said relevant authorities have yet to reach a conclusion on the actual situation of the disease throughout the country.

He added officials were looking into bird flu possibilities in every province.

Having hit by two rounds of bird flu outbreaks, the government has placed fighting the disease as the country's top priority and set Oct. 31 as the deadline to eradicate bird flu from the kingdom.

The poultry epidemic has caused great economic loss including at least 30 million birds culled in first outbreak and more than 100 million US dollars has been spent for compensation.

During the two outbreaks, the disease have claimed lives of 11 Thais with the kingdom having been fully alerted over a "probable human-to-human transmission" case.