(CNN)
Updated: 2004-02-09 08:45

A US official has slammed a decision by several Asian nations to ban American poultry after chickens on a farm in the eastern state of Delaware were diagnosed with bird flu.

Japan, Malaysia and Singapore joined South Korea in banning all poultry imports from the United States over the weekend, while Hong Kong suspended imports from the affected state only.

The infected flock of about 12,000 birds -- all destroyed Saturday morning -- belonged to a private farmer in Delaware who sold chickens in live markets in New York city.

Japan and South Korea say they are awaiting further information on the US outbreak before deciding whether to lift the ban.

Delaware's agriculture secretary said Sunday the Japanese and South Korean bans on U.S. poultry were "unfortunate" because the bird flu virus found on the farm is contained and does not infect humans.

"I understand the concern because of what's taking place in other parts of the world, especially in Asia," Secretary Michael Scuse told CNN.

"It's unfortunate that our trading partners would take this stance."

About 10 percent of all of Japan's poultry imports come from the United States, while for South Korea it is close to 50 percent.

Much of that chicken comes from the multi-billion dollar industry on the Delmarva peninsula shared by Delaware, Maryland and Virginia.

While Scuse said he was "fairly confident" the virus had not spread, flocks within a two-mile radius of the infected farm were being tested, with results due as early as Monday.

A thorough investigation is being carried out to see how the chickens got bird flu. Outbreaks in the Delmarva area are uncommon but not unheard of, according to Scuse. This case is the second in 10 years for Delaware.

US authorities said the H7 strain of bird flu found on a private farm in Delaware's south does not infect humans.

The H5N1 strain of bird flu, on the other hand, has killed at least 18 people in Thailand and Vietnam, and forced the slaughter of tens of millions of chickens across Asia.

In Asia, the World Health Organization says bird flu has been detected or suspected at farms in more than a dozen areas in China, but no human cases have been reported.

Meanwhile Reuters news agency quoted a Hong Kong doctor as saying that up to 70 percent of people who contracted bird flu in the latest outbreak have died, making it twice as deadly as the last outbreak in 1997.

UN experts are investigating whether the bird flu has spread to pigs, after a Vietnam representative of the U.N. Food and Agriculture Organization said Friday preliminary tests found the virus in the snouts of pigs in Hanoi.

But the results do not necessarily mean the swine are infected, the agency added, saying the nasal swabs may just be confirming the presence of infected chicken dropping on their snouts.

More rigorous tests, looking for the virus or antibodies in the blood, still need to be carried out.