The World Health Organisation said Friday that 18,156 people had died from swine flu, a year after the influenza was declared a pandemic.

The virus is now "globally less active," Gregory Haertl, a spokesman of the UN health agency told AFP, but he warned that children and pregnant women in particular should remain vigilant.

Haertl also said that the figures on swine flu are "without doubt underestimated. It will be probably several times more than that."

"It is difficult to say what is the exact number, we'll have it within two years" after the disappearance of the virus, he added.

The WHO has been defending its handling of the pandemic in recent weeks, with a top medical journal becoming the latest to challenge it earlier this month.

The British Medical Journal found that WHO guidelines on the use of antiviral drugs were prepared by experts who had received consulting fees from the top two manufacturers of these drugs, Roche and GlaxoSmithKline (GSK).

But the head of the WHO defended the agency, rejecting claims that its handling of the pandemic was marred by commercial interests.

"At no time, not for one second, did commercial interests enter my decision-making," said Margaret Chan, WHO director-general, in a letter sent to the British Medical Journal, following the publication's article.