Global health officials looked at ways Friday to battle swine flu as confirmed cases grew worldwide and one senior official suggested the spread of the virus could become "unstoppable."

The meeting attracted health ministers from countries including Canada, the U.S., China, and Britain. It was held in Cancun, where tourism has plummeted since April when the H1N1 virus first appeared in Mexico.

As the gathering got underway, officials were told the world could face difficult realities in tackling the virus.

"With well over 100 countries reporting cases, once a fully fit pandemic virus emerges, its further international spread is unstoppable," World Health Organization director-general Dr. Margaret Chan said during opening remarks on Thursday.

The WHO said that as of Thursday, the number of officially confirmed swine flu cases worldwide had reached 89,921 and that 12,720 new cases had been reported since Wednesday.

About half of the new cases were in the United States, although Britain, Chile, Mexico and the Philippines also reported large numbers of new cases.

Britain, which has officially reported 7,447 swine flu cases, has emerged as the hardest-hit nation in Europe.

When the conference opened, British officials raised the possibility that by the end of August, 100,000 new cases of swine flu could be reported each day, the BBC reported on its website.

Prediction disputed

Experts, however, questioned the prediction, suggesting the threat of swine flu could fade as the weather cools in the fall months.

"It seems like a lot of mathematical modelling and not too much common sense," said John Oxford, a professor of virology at St. Bart's and Royal London Hospital.

Mexico, meanwhile, is starting to see an increase in swine flu cases in isolated areas. In southern Chiapas state and the state of Yucatan, cases have jumped more than 50 per cent.

In the space of a week ending Tuesday, the number of cases in Yucatan state jumped from 683 to 1,362, and in Chiapas from 492 to 1,079, Mexico's Health Department said.

Mexico has confirmed 10,687 cases to date, including 119 deaths.

Mexican officials had pushed for the meeting to be held in Cancun to highlight the country's success in controlling its epidemic with a five-day national shutdown of schools and businesses in May. With the Southern Hemisphere in the midst of its winter flu season, Chan said officials are keeping a close watch on those countries.

In Chile, cases of the virus have swelled to 7,342, including 15 deaths. The government has predicted it could see as many as 140 children hospitalized a day.

Argentina has 1,587 cases and 26 deaths. This week, the government announced that starting next Monday all schools would close nationwide for an extended winter break.