More than 2,500 traders from Southeast Asia have been banned from working at a jewellery and watch fair here because of fears of a deadly respiratory disease, fair organisers said Wednesday.

The announcement followed a decision late Tuesday by the Swiss government to ban traders from China, Hong Kong and Singapore from taking part in the World Watch, Clock and Jewellery Fair 2003 in Basel and Zurich from April 3-10.

The ban does not affect visitors to the trade fair, one of the top gatherings for the watchmaking industry worldwide, said the event's president Rene Kamm.

On Wednesday, the Geneva-based World Health Organization (WHO) warned against travel to Hong Kong and neighboring Guangdong province in southern China due to the outbreak of atypical pneumonia.

Travellers from those areas are also subject to health checks on their departure.

Kamm said about 400 stands for companies from China, Hong Kong and Singapore would stay closed, affecting about 2,500 to 3,000 staff.

He told journalists that the measure would shut about two-thirds of the stands at the exhibition hall in Zurich.

"We will close these stands because people arrived after March 1," Kamm said.

The Swiss government decree forbids people who have been to China, Hong Kong and Singapore since the beginning of March from working at the fair.

"Personally I regret this restriction, and it doesn't concern visitors," Kamm added.

A representative for Hong Kong's Trade Development Council, Fred Lam, said the ban had shut down business for the 317 exhibitors in the Hong Kong pavilion, the second largest at the international fair.

"It is most disappointing that the Swiss government issued the decree after most of the Hong Kong exhibitors had arrived in Switzerland or were on flights, and without prior consultation," Lam said.