Geneva: The deadly SARS (Severe Acute Respiratory Syndrome) outbreak in China and Hong Kong could cause long-term damage to the regions economic growth and knock-on effects for the rest of the world unless it is brought quickly under control, the World Trade Organisation (WTO) said on April 23.

Already the situation is affecting tourism and business travel, but it could soon start striking at wider business and investor confidence, said Michael Finger, of the WTO's development and economic research division.

SARS already has killed at least 251 people, the huge majority in China and Hong Kong. More than 4,000 cases have been reported worldwide - more than half of those in China alone.

"There was an immediate effect on tourism, hotels and air transportation, but perhaps the most dramatic impact would be a change in confidence and perspectives and how this translates afterward into investment behaviour," Finger said.

"It will be quickly felt throughout the economy. The biggest problem will be if it creates some panic reactions. What we hear now in Beijing that the children have to stay at home could have an impact on the confidence of consumers and investors."