HAIKOU, July 9 -- As China attempts to register the Maritime Silk Road with UNESCO, protection of archeological sites in the South China Sea is underway.

Shipwrecks around Shanhu and Jinyin islands in the Xisha archipelago will be excavated over the next two years, Wang Yiping, head of cultural heritage for Hainan Province, told Xinhua. Stone building material and carvings dating back to the Qing Dynasty (1644-1911) have been discovered at the sites.

The material may have been carried by unfortunate Chinese emigrants whose ships sank. Such immigrants are known to have constructed traditional Chinese homes and temples at their destinations in Southeast Asia.

Sansha City, which administers the Xisha Islands, has had conservation programs on Ganquan and Beijiao islands since earlier this year, Wang added. China has conducted frequent archeological surveys around the Xisha Islands, and the survey is now expanding south to the Nansha Islands.

"A national underwater archaeological base, a working station and a museum related to the South China Sea are all planned to protect the Maritime Silk Road and help add it to the UNESCO World Heritage list," he said.

The trade route emerged during the Qin and Han dynasties (BC 221-AD 220). It began on China's east coast, principally Quanzhou City in Fujian Province, and crossed the South China Sea and the Indian Ocean to reach the Mediterranean.

More cities have joined Quanzhou's application for UNESCO World Heritage status since it was first mooted in 2002. A total of nine, including Nanjing and Ningbo, are now on the tentative world heritage list. Last month, the nine cities issued a joint declaration strongly advocating inclusion of the South China Sea section of the Maritime Silk Road on the tentative list.

Hainan will lead the other six provinces in pushing forward the UNESCO World Heritage application, said Zhu Hansong, head of the provincial department of culture.

"For underwater protection, cooperation can be in the fields of excavation, information sharing, geophysical technology and personnel exchanges," Wang said.

Cultural heritage authorities have located 136 underwater sites in the South China Sea since a protection initiative started in 1990, and many of the sites are included in the national protection list.

Porcelain, carvings and coins excavated from the sites originate from the Southern, Song, Yuan, Ming and Qing dynasties. This shows that China had the navigational ability to reach the South China Sea islands at that time.

Excavation has been restricted due to financial constraints, lack of professionals and looting. The average depth of the South China Sea is 1.2 kilometers, adding to the difficulties, said Li Jilong, a researcher from the provincial cultural heritage bureau.

"World heritage registration is fundamental to protecting and developing the archeology of the South China Sea. We hope the world recognizes the real value of the area," Zhu said.