WHO watching Japan flu cases closely

GENEVA (Reuters) - The World Health Organization is closely monitoring the situation in Japan after three students from the same high school who had not traveled abroad came down with the new H1N1 flu, a senior WHO official said on Saturday.

The city of Kobe is closing some schools for a week after eight people, including the three students, were confirmed as being infected with the disease, also known as swine flu, Kyodo news agency reported.

"We are just watching the developments very carefully," acting assistant Director-General Keiji Fukuda told reporters.

But Fukuda said it was not clear at this stage whether the outbreak in Japan would cause the WHO to declare a full pandemic, raising its alert level to the top of a 6-point scale.

The WHO raised its pandemic alert on April 29 to 5 on the scale, meaning a pandemic is imminent. Proof the disease was spreading in a region outside North America, where it originated, would trigger an increase to 6.

"If we go to phase 6 the events could happen anywhere, they could happen in Europe, they can happen in South America, they could happen in Asia," he said.

Earlier the WHO reported the number of confirmed cases of H1N1 flu had climbed to 8,451, including 72 deaths.

The number of countries reporting confirmed cases of H1N1, has risen to 36 with Ecuador and Peru confirming their first cases, the WHO said in its daily update.

The vast majority of cases have been in Mexico and the United States.

WHO Director-General Margaret Chan said on Friday there remained "great uncertainty" about the new strain, which continues to spread and could pose particular threats in Southeast Asia.

U.S. health officials later on Friday announced they were easing their warning on travel to Mexico.

The virus is behaving much like a seasonal influenza strain -- spreading rapidly and causing mainly mild disease, but severe illness in some people.

Seasonal flu kills 500,000 people a year, mainly the elderly or those with respiratory problems like asthma.

The WHO said Mexico has reported 2,895 confirmed cases including 66 deaths. The United States has reported 4,714 confirmed cases including four deaths. Canada has 496 confirmed cases and Costa Rica nine cases, both with one death.

The WHO's tally lags national reports but is considered more secure. Rising numbers can indicate that a backlog of cases is being processed, as well as the spread of the disease.

Since Saturday's WHO figures were collated, Turkey has confirmed its first two cases, and India confirmed its first case.

(Reporting by Jonathan Lynn and Jason Rhodes; Editing by Dominic Evans)