"Only one third of the 3,950 miles of wall now exists and the length is still shortening," the official Xinhua news agency said, citing a recent report.

"Improper repair is just one kind of destruction," Dong Yaohui, general-secretary of the Great Wall Society of China was quoted as saying.

"It's much better to keep it as it was if we can't repair it properly."

The number of visitors -- ten million a year -- also has contributed to wear and tear, Dong said, calling on tourism departments to "find a balance between development and protection."