World Health Organisation expert advisers could on Tuesday determine that the H1N1 flu pandemic is fully over, or may deem it is still circulating in the southern hemisphere and therefore a global threat.

The WHO's emergency committee is due to meet by teleconference from 1200 GMT.

"They are going to look at the info and see what the epi (epidemiological) info says around the world," WHO spokesman Gregory Hartl told reporters in Geneva.

"The two most likely outcomes are either status quo or 'post-pandemic'."

This would mean the experts could skip the "post-peak" phase in the WHO's pandemic scale, which has been at the top level of 6 since June 2009, and recommend that WHO director-general Margaret Chan move the alert level directly to "post-pandemic".

The UN agency's guidance on whether a disease constitutes a pandemic determines how its 193 member governments handle an outbreak, including stockpiling vaccines and antivirals.

Hartl stressed that the virus remained threatening to some vulnerable people, notably pregnant women, young children and those with respiratory problems, and would continue to require vaccinations for at-risk groups.

"It is predicted that H1N1 will continue to be the primary or overwhelming virus among influenza viruses for quite a while," he told journalists.

"Pandemic or no pandemic, H1N1 will still exist. If there is no pandemic, it means that H1N1 is behaving like a normal flu virus."

The WHO has been accused of exaggerating the dangers of the H1N1 outbreak, which was declared a full pandemic in June 2009 after emerging two months earlier in April.

Symptoms suffered by most people infected with the virus, widely known as swine flu, have been mild. But WHO experts fear it could spread easily among people if it were to mutate into a more dangerous or lethal form.

Laboratory tests have confirmed more than 18,000 deaths from H1N1 infection, according to WHO figures, but the actual global death toll is much higher and will take at least a year after the pandemic ends to establish.

The virus is currently most active in parts of the Caribbean and Southeast Asia, with ongoing infections in parts of Chile.

The emergency committee has been waiting for signs of how the virus is developing in the southern hemisphere winter before making a full pronouncement on its state.

No news conference is scheduled after the committee meeting, which involves experts from around the world. A statement will be posted on the WHO website late on Tuesday or early on Wednesday, the WHO said. – Reuters