Liu Huilin, deputy director of the Dunhuang Research Institute, said the centre will provide visitors with a "virtual grotto tour" during which they will be able to watch videos, learn about the grotto's history and gain basic knowledge about how it should be protected.

"If tourists can gather the information they need before entering the grottoes, their stay inside will be shortened and that will be beneficial for the grottoes' preservation," Liu said.

Currently, every tour group accompanied by a guide spends an average of five to 10 minutes inside the grottoes, given that the guide has to recount their history, he said.

In the peak season, visitors swarm inside one after the other, provoking sudden increases in temperature, humidity, and carbon dioxide and dust levels. This seriously threatens the survival of the painted frescoes and sculptures, Liu said.

Last year, 310,000 visitors visited the site, mostly during the week-long May Day and National Day holidays.

According to Liu's institute, annual visitor numbers could reach half a million in the next five to 10 years.

To minimize the potential damage inflicted by visitors, the research institute has commissioned three companies in Beijing, Shanghai and Lanzhou to design a layout for the new customer service centre.

If everything goes smoothly, Liu said, the centre will be operational before 2006.

Caves containing more than 50,000 sutras, documents and paintings in the Mogao Grottoes in Dunhuang were first made public in 1900. The works are from nearly 10 dynasties, covering the period from the 4th to the 11th century.

The Mogao Grottoes were included on the United Nations Educational Scientific and Cultural Organization World Heritage List in 1987.

(China Daily April 16, 2003)