The SACH official was responding to the hot dispute in Chinese society about whether the Qianling mausoleum should be excavated.

Located 80 kilometers northwest of the ancient city of Xi'an, capital of northwest China's Shaanxi Province, Qianling is the joint tomb of Wu Zetian, who remained in power for 50 years, and her husband, Emperor Li Zhi of the Tang Dynasty (618-907).

It is the only tomb in China which contains the bodies of two emperors. Wu Zetian was buried in the tomb 22 years after her husband.

Qianling is also the best preserved ancient tomb in China and has not been looted, said Liu Qingzhu, head of the Institute of Archaeology under the Chinese Academy of Social Sciences.

All historical attempts to rob the tomb ended in failure which lent even more mystery to Qianling.

Discussions about the excavation of Qianling began many years ago, but applications to open the tomb have never been approved by central government.

At a recent academic symposium, excavation of the tomb became a controversial topic again, with famous archaeologist Shi Xingbang, former director of the Shaanxi Archaeological Research Institute, strongly advocating that Qianling be explored. He pointed out that certain fragile relics will rot undergrounds the years go by.

In the 1980s, Shi participated in the excavation of Famen Temple in Fufeng County, 118 kilometers from Xi'an. He found that all paper relics had rotted and that most of the silk relics were deteriorating.

He insisted that excavation of Qianling be started as soon as possible, claiming that China now has the qualified professionals and technical know-how to do the work.

But other experts argue that China should hold off a bit, saying a plan has to be in place to protect the tomb's treasures before any digging begins.

"Many technical problems need to be settled to protect silk, wooden and paper relics," said Liu Qingzhu.

The silk and paper relics unearthed from other ancient tombs are still kept inside refrigerators, which shows that "we haven't mastered the techniques to protect these relics," said Zhang Jianlin, deputy director of the Institute of Archaeology of Shaanxi Province.

The SACH official said the Chinese government has stood firm on the principle of no active excavation of imperial tombs, and stressed the importance of protection and rescue in doing archaeological work.

Some experts say plans and effective measures to protect the Qianling relics need to be worked out before the tomb is opened.

They insist that technical problems must be resolved first to avoid damage to the tomb's precious contents.