HANOI, Jan 17: The number of Vietnam's confirmed bird flu deaths has risen by one to four, the World Health Organization said, while a hospital in the country's south said on Saturday it had two very sick patients with bird flu symptoms.

The U.N. health agency, which is helping Vietnam battle the fast-spreading disease, said a five-year-old boy, from Nam Dinh province, died on January 8 from bird flu. Nam Dinh is about 100kms south of the capital, Hanoi.

"WHO now counts four confirmed cases of H5N1 in Vietnam," the agency said in a statement issued late on Friday.

Five children remain hospitalised in Hanoi as suspected avian flu cases, but only one is very sick, Peter Horby, WHO epidemiologist, told Reuters Television in an interview.

He said another seven adults suspected of having bird flu were being treated at Hanoi's Bach Mai hospital, but added it was difficult to assess the number of cases as the disease had symptoms similar to other ailments.

"It's not easy to distinguish it from any other severe respiratory disease," Horby said. South Korea, Japan and Taiwan have also reported outbreaks of bird flu but Vietnam has been the hardest hit.-Reuters