"If our measures and vaccinations are successfully implemented, I believe the situation will be very good," he told AFP.

But a Beijing-based World Health Organization (WHO) expert said the virus is known to thrive in cold weather and that vaccination alone could not prevent the spread of the deadly disease.

"We've certainly seen peaks of animal outbreaks and human outbreaks in the winter time," said Julie Hall, a communicable disease expert at WHO's office in the Chinese capital.

"We should be prepared this winter as the temperature drops. It's possible we can see animal outbreaks and along with that human cases."

Changes in weather could also fuel the spread of the disease as birds, which carry the virus, start migrating.

Agriculture ministry officials at the news conference vowed to continue an ambitious drive to vaccinate all of China's poultry, despite warnings from experts that vaccinations could mask the virus.

"The only way to prevent the spread of bird flu is to step up vaccinations," Zhang Baowen, the vice minister of agriculture, told reporters.

China embarked on a vast program to vaccinate its entire stock of poultry -- the largest in the world -- in November 2005 after several outbreaks across the country.

Officials said their aim was to vaccinate almost the entire annual stock of 15 billion poultry this year.

However, vaccinated poultry can still carry the H5N1 bird flu virus and spread it, experts have said. Hardly any of the human cases of bird flu in China were preceded by poultry outbreaks.

"We hope that what they're doing is not just vaccinating but strengthening the surveillance system, looking at the movement of animals," Hall told AFP. "You cannot really rely on vaccination alone."

China's last outbreak of bird flu among poultry occurred in early August when ducks began dying at a farm in Changsha city, Hunan province in central China.

So far, 21 people in China have contracted bird flu and 14 of them died, with the most recent fatality occurring in July, according to official figures.

The disease has killed about 140 people, mostly in Asia, since the current outbreak started in 2003.

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