Beijing officials are denying a report by a British magazine that said the bird flu outbreak originated in China several months ago.
A report Wednesday in the British weekly magazine, New Scientist, said the bird flu first appeared in China, probably in early 2003.
The report quoted a World Health Organization official as saying samples taken last year turned out to be the exact strain of the H5N1 virus that has recently appeared in poultry across much of Asia.
On Thursday, Chinese officials responded angrily to the report. Zhang Qiyue is the Foreign Ministry's spokeswoman.
At a regular briefing Thursday, Ms. Zhang called the suggestion that China had covered up a bird flu outbreak inaccurate, groundless, and disrespectful of science.
World Health Organization spokesman Roy Wadia in Beijing cautioned against placing blame on anyone for the flu outbreak just yet.
"We don't feel that it's really useful to point fingers and talk about a cover-up," he said. "Let's combat the situation first, and then when the crisis is hopefully over, let's take a look back at how these situations were handled in China and the other countries, and see what we can learn from that."
China has confirmed the presence of the bird flu virus in three provinces -Guangxi, Hubei, and Hunan. State media on Thursday said authorities had placed 23 people under medical observation after they had contact with infected fowl.
The government has begun culling tens of thousands of chickens and ducks in a bid to stop the disease's spread.
The World Health Organization has urged nations to slaughter all poultry near infected areas, saying that is the best way to prevent the spread of the virus.
In addition to being deadly to poultry, the virus is a threat to humans. Several people have been infected after coming in contact with sick birds in Thailand and Vietnam. Health experts fear the bird virus could change so that it can spread from human to human.
India on Thursday joined a growing list of countries that have banned poultry imports from Asian countries infected with the bird flu.
Indonesia on Thursday ordered a mass slaughter of chickens in areas where the virus has appeared. The country had earlier refused to do so, fearing damage to its $7 billion poultry industry. Government officials say chicken farmers will be compensated for their losses.
Places that have not been affected thus far are stepping up measures to keep out the disease. Hong Kong authorities Thursday quarantined a woman who showed signs of pneumonia after arriving from Vietnam, while Singapore intensified a campaign to kill crows.