Officials in the Philippines say a 49-year-old woman with swine influenza A-H1N1 has died - the first death in that country related to the virus.

Health authorities say the woman died Friday from heart failure that was aggravated by severe pneumonia. They said throat swabs collected after her death revealed she had the swine flu virus as well.

But Philippine Health Secretary Francisco Duque said health authorities cannot conclude the woman's death was due to the virus.

This particular strain of influenza is a new virus that has shown itself to be very contagious, spreading easily among people, and from one country to another.

The World Health Organization earlier this month declared an influenza pandemic for the first time in more than 40 years, as cases of the swine flu continue to spread worldwide.

The WHO says more than 52,000 cases of swine flu and 231 deaths related to the virus have been confirmed worldwide. The latest figures do not include the death in the Philippines.

Some information for this report was provided by AFP and AP.