China has banned its athletes from taking part in advertising and public relations work, local media reported on Thursday.

"In order to prepare for the 2008 Beijing Olympics, our country's athletes, including celebrity athletes, are banned from participating in all kinds of social activities," the China Sports Daily quoted Sports Minister Liu Peng as saying.

"Athletes who participate in social activities are relatively easily distracted. If this is not regulated, it may interfere with their training and be detrimental to Beijing Olympic preparations," Liu said.

The report did not specify what he meant by "social activities" or which kinds would be deemed necessary but observers said they included commercial endorsements.

China holds its athletes to strict standards of conduct that have become especially severe in the run-up to the Olympic Games.

Olympic diving gold medallist Tian Liang was kicked off the national team in 2005 for taking part in a rash of television ads and endorsements.

In May, Olympic champion hurdler Liu Xiang came under fire for signing a deal with the Baisha corporation, a Chinese tobacco giant that sells 75 billion cigarettes a year.

A book entitled, "My Heart is Flying: A Liu Xiang Photobook," published in February, contained dozens of images of cranes, the birds that adorn Baisha cigarette cases.