The number of laboratory-confirmed cases of the swine flu or A(H1N1) virus has increased to 4,694 - double from the last Friday's figure - and also claimed 53 lives around the world, the World Health Organization (WHO) has said.
According to latest WHO update, Mexico and the US have topped the list of 30 countries where laboratory-confirmed human cases of the virus have been reported. Mexico has 1,626 cases with 48 deaths while the US has 2,532 with three deaths.
"WHO's pandemic alert level remains at Phase 5 - on a six-point warning scale - as it has for the past several days," Dr Keiji Fukuda, WHO's Acting Assistant Director-General for Health Security and Environment said.
"Community-level sustained human-to-human transmission has been documented in North America, in Mexico and in the United States most clearly. We do not see clear evidence of sustained community-level transmission going on in other countries yet," he said.
Dr Fukuda noted that it is possible that the alert level will go up to Phase 6, which would mean that the spread of the virus has become established in another region outside of North America and is spreading at the community level.
At the same time, the current situation could stabilise where it is now, or the alert level could even go back down to Phase 4 in the future.
The agency said it is mindful of the many travel-related cases that have now been reported from a large number of countries in almost all regions of the world.
WHO is not recommending travel restrictions related to the current outbreak, but individuals who are ill should delay travel plans and returning travelers who fall ill should seek appropriate medical care, the agency noted on its web site.
"This is still unfolding," noted Dr Fukuda. "We are still evaluating the clinical features, the epidemiology and the spread, and we will continue to evaluate what is the impact on both people and countries."
He added that much of what is going on now reflects the fact that so much planning and preparedness has gone on for the past few years.
"I think it is still a confusing situation. We cannot come to you and say we understand everything which is going on."
"But I do believe that if we had not had all of those preparations, if we had not worked so hard to get information out quickly, if countries had not been thinking about what to do in this kind of situation, in fact we would have had much more confusion and in many ways the severity would have been greater," he stated.
"We will continue to work as hard as we can to make sure that countries are as prepared as possible."