The Chinese government refuses to relinquish its claim to the repatriation of an estimated 50,000 Bronze Age relics from the Yin Ruins, including examples of the earliest written Chinese characters, a government cultural official said?on Thursday.

The official with the State Administration of Cultural Heritage was speaking as the Yin Ruins were added to the World Heritage List at a meeting of the United Nations Environmental, Scientific and Cultural Organization (UNESCO) World Heritage committee, in Lithuania's capital, Vilnius.

Located in Anyang, central China's Henan Province, the Yin Ruins are the earliest remains of an ancient capital city in China, which can be dated back 3,300 years to the Shang Dynasty (1,600 BC to 1,100 BC), also known as the Yin Dynasty.

Since its excavation in the early 20th Century, over 150,000 tortoise shells and animal bones bearing inscriptions that recorded harvests, astronomical phenomena, worship rituals and wars have been unearthed.

Tang Jigen, an archaeologist leading the research at the Institute of Archaeology under the Chinese Academy of Social Sciences, said at least 50,000 relics had been stolen and smuggled abroad since the site's discovery.

In the early 20th Century, foreign missionaries and explorers bought a large number of antiquities of Yin Ruins from the local residents at very low prices and smuggled them to their own countries, said Tang.

And during the wars of foreign invasion in the first half of 20th Century, the Yin Ruins suffered greater losses, Tang said.

When the Japanese army occupied Anyang in 1937, the Yin Ruins were looted by the invaders many times, and all of the treasures were removed to Japan, Tang said.

More than 10,000 tortoise shells are now housed in Japan, Tang added.

He estimated that at least 80 museums, foundations, auction agencies and private collectors all over the world had Yin antiquities, including precious tortoise shells, and bronze, pottery, jade, bone and stone objects.

Tang said Japan, Canada, the United States, Britain, Germany, France, Russia and Sweden had the largest number of collection of Yin antiquities.

Li Peisong, vice director of Museum Department of the State Administration of Cultural Heritage, said China retained the right under international conventions to claim the return of the antiquities from Yin Ruins lost overseas.

Li said although the United Nations had passed conventions on the return of relics looted during war to the original country, the countries that benefited from war adopted an "ambiguous" attitude.

Their reluctance to return the treasures was the major obstacle to fulfill the conventions, Li said.

The Yin Ruins witnessed the prime of China's Bronze Age. They are home to the biggest bronze item ever discovered, the Simuwu Ding, an 875-kilogram four-legged pot.

Experts say some unique Chinese traditions also originated from the Yin Ruins, like the symmetric city layout, which has been followed by most Chinese cities, including Beijing, for more than 3,000 years.

Tang said many of the treasures collected by Japanese, Canadian and American museums are regarded as symbols of Yin and ancient Chinese culture.

He said the figure of 50,000 was a conservative estimate, because many organizations and private collectors didn't publicize their collection.

Since the founding of New China in 1949, more than 20 excavations have been carried out at a dozen different areas of the site. Some of the findings, such as bronze items unearthed in the 1970s from the tomb of the woman general Fuhao and the oracle bones found near Xiaotun Village, are among China's major archaeological discoveries.

Over 60 years of excavation and study of the site have enabled archaeologists to identify the scope and general layout of the ruins.

Excavations at Yin Ruins have revealed tombs, palace and temple foundations along with bronze ware, jade carvings, lacquer, white carved ceramics, green-glazed china, and oracle bones.

Li Peisong said no further excavations would be carried out at the Yin Ruins unless there was a special reason.

Experts believed that keeping the treasures underground and intact is the best way to preserve them.

(Xinhua News Agency July 14, 2006)