Global production of swine flu vaccines will be "substantially less" than the previously expected, the World Health Organization said Friday.

Production will be lower because some manufacturers are still turning out vaccines for seasonal flu, WHO spokesman Gregory Hartl told reporters in Geneva.

The number of doses will fall short of the 4.9 billion doses the global health body previously hoped could be available for the pandemic, Hartl said.

The United States, France, Britain and six other countries announced Thursday that they will share part of their vaccine supply with poorer countries.

WHO welcomed the move Friday, saying it "demonstrates the commitment of these countries to fairness in sharing of scare resources."