The offer was made during a meeting between U.N. officials, vaccine makers and other health experts to discuss how to provide vaccines to poor countries if the swine flu outbreak goes global. But it has not been finalized by either GlaxosmithKline PLC or WHO.

On Tuesday, U.N. head Ban Ki-moon and WHO chief Margaret Chan appealed to drugmakers to save some of their pandemic vaccines for poor nations. Several vaccine makers in developing countries have also offered to share some of their vaccines, but their production capacity is limited.

Glaxo spokesman Stephen Rea said that in addition to the vaccine donation, the company will also reduce its pandemic vaccine prices for developing countries.

No pandemic vaccine exists yet, but pharmaceuticals say they can begin production immediately once they get the vaccine's key ingredient, a "seed stock" based on the virus. That is being developed by the United States' Centers for Disease Prevention and Control, and should be available by mid-July, WHO said.

Once vaccine makers receive the seed stock, a vaccine should be available in several months.

Glaxo has also signed agreements with various countries to provide them with pandemic vaccine as soon as it's available. It has promised to provide 60 million doses for Britain, 12.6 million doses for Belgium and 5.3 million doses for Finland. It is also waiting to finalize a deal with France that would provide them with 50 million vaccines.

So far, other big vaccine makers have not followed suit with offers to donate. Swiss pharma giant Novartis AG said its position remained unchanged since the question of vaccine access for poor countries first came to the fore in connection with the H5N1 bird flu.

"It's pretty much the status of discussions two years ago," spokesman Eric Althoff said.

"I don't think that all of the answers are there yet."

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