The H5N1 strain extracted from swine in the southeastern province of Fujian last year was "extremely small" and no mutation of the virus into a form more dangerous to humans had been observed, the state-run Beijing Times said.

The report was the latest cautious official attempt at clarification following the surprise announcement by a respected scientist last week that H5N1 had been detected in pigs in 2003 for the first time ever.

The scientist, national bird flu laboratory director Chen Hualan, was quoted by the paper as toning down the possible implications of the discovery.

"Actually, the amount of bird flu virus isolated by our laboratory from pigs in Fujian was extremely small," she told the paper, emerging from days of silence after talking to journalists in Beijing last week.

"The probability of isolating H5N1 virus from pigs was less than one in a thousand," she said.

On Friday Chen had said H5N1, which has killed 27 people in Asia this year, was discovered in pigs both in 2003 and 2004. She called it "a rather dangerous signal in terms of public health."

Researchers fear that infection among pigs could be the first step in a mutation of the virus into a form that could spread more easily to humans. Until now H5N1 had been found only in poultry.

The United Nations Food and Agriculture Organization (FAO), in charge of UN communications with the agriculture ministry, was eager to get as much information as possible.

"This is a big concern and that's why we are keeping in close contact with the ministry of agriculture," Sun Yinhong, a Beijing-based program officer for the FAO, told AFP.

Shortly after Chen's announcement, the FAO asked the agriculture ministry how many pigs were found to carry the virus, where and how.

This series of specific questions was met with a very general answer to the effect that bird flu had not been discovered in pigs, according to Sun.

On Monday the agriculture ministry publicly confirmed for the first time that the deadly strain of bird flu was found in pigs last year.

The Beijing Times quoted an unnamed agriculture ministry official as saying the smattering of H5N1 found in pigs so far was far from being epidemic in proportion.

"The discovery or isolation of virus in pigs does not mean that they are actually infected, and it certainly does not mean that a bird flu epidemic has broken out in the area," the official said.

The paper only addressed the occurrence of bird flu in pigs in 2003, and made no mention of Chen's remark last week that it had reemerged in swine this year too.

Chen hung up the phone when contacted Tuesday.

The agriculture ministry, which declined repeated requests for comment Monday and Tuesday, failed to provide detailed clarification.

Academic papers published in little-known journals gave some hints of exactly what was discovered in China last year.

H5N1 was detected in pigs at four different locations near China's east coast in April 2003, according to a four-page article in the May issue of the Chinese Journal of Veterinary Science.

"If bird flu enters into pigs and, once inside their bodies, acquires the ability to transmit among mammals and then enters into the human population, it will not just mean a few deaths or a few dozen deaths," the authors wrote.

"If there is no technological or preventive preparation, it would be dreadful to contemplate!" they added, departing from the normally disinterested prose of academic literature.

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