London ? In a drive to inoculate people against swine flu before winter, many European governments say they will fast-track the testing of a vaccine, arousing concern among some experts about safety and proper doses.

The European Medicines Agency, the EU’s top drug regulatory body, is accelerating the approval process for swine flu vaccine, and countries such as Britain, Greece, France and Sweden say they’ll start using the vaccine after it’s greenlighted — possibly within weeks.

In an interview with The Associated Press, Dr. Keiji Fukuda, the World Health Organization’s flu chief, warned about the potential dangers of untested vaccines, although he stopped short of criticizing Europe’s approach outright.

Flu vaccines have been used for 40 years, and many experts say extensive testing is unnecessary, since the swine flu vaccine will simply contain a new ingredient: the swine flu virus.