"We are still living in a situation where the depth and the length off this economic challenge is not clear yet," the body's acting Secretary General Taleb Rifai told reporters in Madrid, where the organisation is headquartered.

The organisation said 117 million tourist arrivals were registered in January and February, 7.7 per cent fewer than for the first two months of 2008.

The reduction follows a drop of two per cent in arrivals in the second half of 2008.

It said Europe was the hardest hit region, suffering a decline of 8.4 per cent while North America experienced a reduction of 3.4 per cent.

Rifai said it was still too early to say what effect the recent outbreak of swine flu would have, given that it had only begun to unfold over the past few weeks.

But he said past experience with health threats, such as the 2002 outbreak of severe acute respiratory disease, or SARS, in Asia, showed tourism is capable of recovering rapidly once a threat is brought under control.

Rifai said the World Tourism Organization expected international tourism to decline by up to two per cent over the year.

The organisation said the figures Tuesday did not include receipts from tourism but that these normally followed the trend of arrivals. It said it would have complete figures in June.

- AP