Until now, deaths have been confined to Mexico, where more than 150 have died and well over 2000 taken ill.

The flu death of a 23-month-old child in Texas was confirmed yesterday by the acting director of the Centre for Disease Control and Prevention, Dr Richard Besser.

The disease has now swept the world, with British Prime Minister Gordon Brown confirming yesterday three more cases of swine flu had been confirmed in Britain.

Elsewhere, there were 13 confirmed cases in Canada, one in Costa Rica (and three suspected), two in Israel, three in New Zealand (with another 42 suspected) and two in Spain (with another 32 suspected).

Australia has 91 suspected cases of infection; Austria five; Chile eight; Colombia nine; Denmark five; France 20; Germany two; Hong Kong four; Indonesia one; Ireland three; the Netherlands several; Poland three; South Korea six; Sweden five; Switzerland five and Thailand one.

Mr Brown said British authorities aimed to increase stocks of anti-virals from 35 million to 50 million.

The world has no vaccine to prevent infection but United States health officials aim to have a key ingredient for one ready early next month, the big step that vaccine manufacturers are awaiting.

But even if the World Health Organisation ordered emergency vaccine supplies and that decision has not yet been made it would take at least two more months to produce the initial shots needed for human safety testing.

The US Food and Drug Administration's swine flu authority, Jesse Goodman, said, ''We're working together at 100 miles an hour to get material that will be useful.''

US President Barack Obama asked Congress for $US1.5 billion ($A2billion) in emergency funds to help build more drug stockpiles and monitor future cases, as well as help international efforts to avoid a full-fledged pandemic.

Cuba and Argentina banned flights to Mexico. Mexico's health secretary Jose Cordova said, however, the country's death toll from swine flu was ''more or less stable''.

Mexico City, one of the world's largest cities, has taken drastic steps to curb the virus's spread, closing schools, gyms and swimming pools and telling restaurants to limit services to take-away meals.

The number of confirmed swine flu cases in the United States rose to 66 in six states.

In New York, the city's health commissioner said ''many hundreds'' of schoolchildren were ill at a school where some students had confirmed cases.

New Zealand had 14 cases confirmed by health authorities.

Health Minister Tony Ryall said World Health Organisation lab tests in Melbourne confirmed three cases of swine flu among members of a school group recently returned from Mexico who showed flu symptoms.

Officials decided that was evidence enough to assume all were infected.

Senior regional health official Dr Julia Peters said yesterday the tally had risen to 14 overnight because two more students in the group and another traveller who recently returned from North America were also believed to be infected.

Israel and Canada have also reported cases.

The WHO argued against closing borders to stem the spread.

The US although checking arriving travellers for the illness who may need care also said it was too late to close countries' borders.

Dr Besser said, ''Sealing a border as an approach to containment is something that has been discussed and it was our planning assumption should an outbreak of a new strain of influenza occur overseas.

''We had plans for trying to swoop in and knock out or quench an outbreak if it were occurring far from our borders. That's not the case here.''

US authorities sought to keep the crisis in context, saying flu deaths were common around the world. The Centre for Disease Control said the new strain was a combination of pig, bird and human viruses for which people might have limited natural immunity.