The production of swine flu vaccines is on track to reach three billion inoculations within the next year, the head of the World Health Organization, Margaret Chan, said on Monday. About 25 companies worldwide are now producing vaccines against the H1N1 virus, Chan said on the opening day of the annual general meeting for WHO's western Pacific region in Hong Kong.

"Most of these companies are in developed countries, but I am very pleased to see some developing countries are also moving into making their own vaccine, and China is one of the first examples," Chan said.

WHO's director general said five companies in China had received official approval to manufacture the vaccine against the virus, which has so far killed about 3,500 people worldwide.

Chan joined health experts from 37 countries and areas in the western Pacific region for the meeting, which runs until Friday.

In addition to the H1N1 pandemic, other topics on the agenda included malaria, HIV/AIDS and the impact of the global financial crisis on health services.