Beijing  - The bird-flu virus is nearly entrenched in China's poultry population and represents a threat to world health, UN experts said Wednesday.

"It has the potential for a pandemic," said Hans Troedsson, the World Health Organization's (WHO's) representative in China, which has the world's largest poultry population.

He told journalists in Beijing after China reported five human bird-flu deaths so far this year that health experts were concerned about the breadth and intensity in China of poultry infections of H5N1, the strain of bird flu that can be deadly in humans.

Most human H5N1 infections have occurred after patients have had close contact with infected birds, but health experts fear the virus could mutate into a form that could easily be passed between humans and cause a worldwide pandemic.

"It is posing a pandemic risk," Troedsson said of the bird-flu outbreak in China's poultry.

"No one can escape it," he added. "It will strike the whole world."

A warning to China of a pandemic also came from another UN agency, the Food and Agricultural Organization.

"We should not be complacent," said Vincent Martin, an animal health adviser from the organization. "If it happens, it will be very scary for everyone."

He called for bird-flu prevention and investigations into how the virus spreads, warning that it was evolving.

The experts said they were also concerned that the most recent human infections in China were widely distributed across the country and could not be linked to nearby outbreaks of bird flu among poultry.

WHO has confirmed 407 human bird-flu cases since 2003 in 15 Asian and African countries, 254 of which were fatal. China has seen 26 deaths from 39 cases, eight of which occurred this year. (dpa)