But it noted that this tally is actually lower than the real number of cases, as countries are no longer required to test and report individual cases.

Swine flu, which was first detected in Mexico and declared as a pandemic by the WHO in June, has so far been characterised by the mildness of symptoms in the overwhelming majority of patients.

According to the WHO, so far there is still no signs of the virus mutating and becoming more fatal despite its fast spreading.

It stressed, however, that the world should keep monitoring the virus and be prepared for any possible changes, especially when winter comes in the northern hemisphere.