The World Health Organization (WHO) said on Friday that universal access to a swine flu vaccine remains a "critical question".

Speaking during a summit on the A(H1N1) virus, WHO assistant director-general Keiji Fukuda said guaranteeing the vaccine is distributed to underdeveloped nations will require "political goodwill."

Fukuda was speaking at the close of the summit, which began Thursday at the Mexican beach resort town of Cancun.

The American continent remains the world region worst affected by the swine flu, which first appeared in Mexico in late April.

The virus has infected 89,921 people in 125 countries and territories and caused 382 deaths worldwide, according to the WHO's latest figures.

"One of the important results (of the summit) was that we recognized that we face technical problems, but also problems of political will," Fukuda said.

Access to a future A(H1N1) vaccine was a central theme of the specially-convened WHO summit, which brought together experts and ministers from about 50 countries.

Cuauhtemoc Ruiz, coordinator for the Pan-American Health Organization, said the vaccine is likely to be available in "three or four months," but it could be up to a year before "sufficient quantities" are produced.

The laboratories working to produce the vaccine, he said, can make 2.5 billion doses in six months.

WHO director-general Margaret Chan said laboratories are looking at various possibilities, including creating a vaccine by adding a new component to the existing vaccine used for seasonal flu.