Asian countries that have so far escaped the bird flu spreading across the continent stepped up measures Thursday to keep the virus outside their borders.

Hong Kong isolated a woman who returned from Vietnam with suspicious pneumonia symptoms and Singapore intensified a campaign to cull crows. The scavengers are considered potential spreaders of the disease, because they could pick up the flu from dead birds.

Hong Kong and Singapore were hit hard by severe acute respiratory syndrome (search) last year and both were on high alert to prevent an outbreak of bird flu, which has affected 10 Asian countries.

Tens of millions of chickens and ducks have died across the region — from the disease or in government-ordered slaughters aimed at containing it. The virus has jumped to humans in Thailand, where two people have died, and Vietnam, which has had eight fatalities.

The World Health Organization (search) insists the mass slaughter of infected poultry is key to controlling the outbreak, but health ministers from 13 infected or threatened countries emerged from an emergency meeting in Bangkok on Wednesday without reaching a consensus that their poultry stocks must be destroyed.

"All countries will adopt the best way to end the spread of this virus as soon as possible. Each country will have to find its own way to end this problem," Thailand's Foreign Minister Surakiart Sathirathai said.

A day after saying it had no such plans, however, Indonesia ordered the mass slaughter of infected chickens. Thailand, which for weeks claimed to be bird-flu free, said the disease was spreading rapidly across its countryside.

Fears that infected people could travel, spreading the virus across borders as happened with SARS, prompted Hong Kong authorities to isolate a 75-year-old woman, sick with flu-like symptoms, after she returned from hard-hit Vietnam.

She was being tested for avian influenza, SARS and other diseases, hospital authority spokesman Cheng Kwong-ying said.

Indonesia's Welfare Minister Jusuf Kalla, meanwhile, said President Megawati Sukarnoputri (search) had promised government assistance to compensate breeders for the losses and to replace their stocks.

"Immediately cull (chickens) that have been infected," Kalla said following a meeting at the presidential palace. "We will then ... help the small-scale farmers whose chickens were killed."

Singapore said it would kill off all of its chicken stocks immediately if a single case is found in the city state, and Taiwan ordered the slaughter of some 50,000 poultry with a mild strain of virus that officials say doesn't infect humans.

The Chinese government promised "resolute" action against bird flu's spread Thursday, stepping up its chicken slaughters, banning poultry exports from three regions and disinfecting cars around a southern town where the virus was found in ducks.

China said it intends to kill all livestock birds within a two-mile radius of infected sites.

Health authorities in Beijing, a city of 13 million people, meanwhile, banned the slaughter of poultry in the capital and prohibited the sale of uninspected meat and poultry products in markets.

Bird flu is believed to be spread by migratory ducks and other wild birds and Singapore will boost its long-running crow culling campaign that has already reduced their numbers from 120,000 in 2001 to about 30,000, environmental spkoesman Satish Appoo said.

Most human cases have been traced to direct contact with sick birds and many victims have been young children.

Although there has been no evidence of human-to-human transmission in the latest outbreak, health officials are concerned the virus might mix with a human influenza strain to create a mutant form that could trigger the next human flu pandemic.

Officials also have said there are no indications so far that bird flu is spreading to people who eat properly cleaned and cooked poultry products, but governments worldwide have slapped import bans on poultry from countries affected with bird flu.

WHO said a human vaccine could be available in about six months.