Beijing has stepped up efforts to stop the sale of illegally obtained Chinese cultural relics by auction houses, collectors and museums.

In the latest case, Yokohama International Auction, in Japan, was informed by China's State Administration of Cultural Heritage on Oct 21 that several Tang Dynasty (618-907) frescoes and manuscripts of Buddhist sutras about to go under the hammer were stolen from China in the past century.

The auction house, founded by a Japanese citizen with Chinese ancestry, canceled the sale. The move was a step in the right direction－no profit was made－but their return to the unidentified client shows stronger international rules are needed.

A new Chinese regulation, released a day earlier, bans the auction of stolen, smuggled or looted relics. It is aimed especially at keeping such relics in China, but it also can be cited as a guideline when dealing with other countries and regions.

Worldwide, many guidelines also have been issued to push collectors to pay more attention to the origin of cultural relics. "The legal circumstances are getting better," according to Huo Zhengxin, a professor of international law at China University of Political Science and Law.

A study by UNESCO shows there are at least 1.64 million sets of Chinese cultural relics scattered across 200 museums in other countries and regions. The China Cultural Relics Academy, an academic organization, estimates the number would be 10 million if private collections were counted.

Many such treasures were looted during wars and other unrest in China from the late 19th century to the early 20th century. Large-scale theft occurred in the 1990s because of the boom in international market demand.