Beijing ? China said Friday that bird flu is spreading among its poultry flocks despite mammoth efforts to control the disease, while leaders at an Asia-Pacific summit warned that greater vigilance is needed to prevent more human infections.

President Bush, Chinese President Hu Jintao, Japanese Prime Minister Junichiro Koizumi and Russian President Vladimir Putin were among the leaders pledging unity in combatting bird flu at the summit in South Korea.

Even isolated North Korea announced it was stepping up surveillance of poultry and launching education campaigns. “Projects to prevent bird flu are deepening further,” the communist regime’s official Korean Central News Agency said.

The near-daily reports of new bird flu outbreaks in China point to the challenges in controlling the virulent virus. Hundreds of millions of birds have been vaccinated, yet the government reported two new poultry outbreaks Friday – bringing to 15 the number of cases it has confirmed since Oct. 19.

In the hard-hit northeastern province of Liaoning, nearly 1 million officials were fanning out to enforce anti-flu controls, which include mandatory poultry vaccinations and twice-daily health checks for all villagers who live near the sites of outbreaks – 72,000 people in all, authorities said at a news conference this week.

Officials have been ordered: “If you get too tired to do your job, close your eyes for a moment and then get back to work,” said Zhou Liwei, a Liaoning government spokesman.

Chickens wait in cages before being slaughtered in preparation for sale Thursday at a poultry market in Wuhan, in China's Hubei province. China reported a new outbreak of bird flu in Xiaogan city in Hubei on Thursday.

At least 67 people have died from the H5N1 strain of bird flu since 2003, most of them in Vietnam, according to the World Health Organization. Most human cases have been traced to contact with sick birds, but experts warn the virus could mutate into a form easily passed between people and spark a worldwide pandemic.

The bird flu threat loomed large at the 21-member Asia Pacific Economic Cooperation summit that began Friday.

Australian Prime Minister John Howard urged countries to put aside “national pride or self-consciousness” and be open about reporting outbreaks.

“The last thing that any nation can afford, not only in its own interests but in the interests of fellow members of the world community, is to in any way hide or cover up the onset of the signs of an outbreak of something that could turn into a pandemic,” Howard said.

The leaders’ final declaration lists preventing the spread of bird flu as a top priority along with free trade and fighting terrorism, according to a draft.

Even as the disease spread among China’s poultry, Beijing said Friday that 174 villagers who came in contact with two people sickened by bird flu show no signs of the disease and have been released from medical observation.

China confirmed its first human cases of bird flu on Wednesday – a woman who died and a boy who recovered. The boy’s sister, who died, is a suspected case. All three had contact with sick poultry.

Chinese officials have blamed migratory birds for many of the nation’s outbreaks and say that vaccinating domestic poultry is their best bet in severing the transmission link between wild and tame birds.