"Right now we don’t believe that we are seeing community transmissions in the same way that we are seeing (them) in the United States or in Mexico," said Keiji Fukuda, WHO acting assistant director-general.

Sustained community transmissions in a region outside the Americas would be a criteria that could prompt the WHO to raise its pandemic alert level from the current phase five to the highest level of phase six.

Phase five signals that a pandemic is "imminent" while phase six would mean that the world is in a pandemic.

Fukuda noted that Spain and Britain are two countries in Europe where relatively large numbers of cases have been reported.

However, the cases in Spain are very closely related to travellers returning from Mexico.

While there are infections in a school in Britain, these remain "related to travel" and have not spread to the broader community, said Fukuda, who added that the WHO is watching developments in the two countries very closely.

Spain’s government said 57 people have been infected while Britain said 27 people have caught the flu.

Overall, the number of people infected with the swine flu virus has reached 1,419, including 30 who have died from the disease, Fukuda said, without giving details on where the additional deaths or infections were occurring.

Earlier Tuesday, the UN health agency said 1,124 cases of influenza A(H1N1) infection had been reported, including 26 deaths.

Fukuda said infections were appearing to affect mostly people who are below the age of 60.

"In general, the bulk of the infections are occurring in younger people. When investigators are looking at the average age range of people getting infected, this is often around the age range of people around their mid-twenties," he said.

It remained unclear whether this is because most of the people who had travelled to Mexico where they caught the disease are generally younger, Fukuda said, adding that it is among questions on the virus that experts are trying to answer at the moment.

AFP / Expatica