Beijing - China is conducting a sweeping crackdown on dissent ahead of this week's awarding of the Nobel Peace Prize to jailed dissident Liu Xiaobo, casting the net wide to prevent friends and family attending.

Liu himself is serving an 11-year jail term for subversion and his wife, Liu Xia is under house arrest. Even family members of little-known dissidents have been prevented from leaving the country.

Lu Yuegang, who lost his job in 2006 at the China Youth Daily following the banning of a supplement for provocative content, said his wife has been stopped from traveling to Hong Kong, where she used to go frequently for business trips.

"Nobody has given a reason. She goes to Hong Kong regularly for work," Lu told Reuters.

"We think it's probably to do with the Liu Xiaobo issue."

In China's frozen northern region of Inner Mongolia, police have detained the wife of one of China's longest-serving but possibly least well-known political prisoners, Hada, ahead of his expected release on Friday, the same day Liu's prize is awarded.

Police have pressured Hada's son Uiles to cut off ties with his parents, promising him 'a nice job, beautiful house and even a pretty girlfriend if he agrees', according to the New York-based Southern Mongolian Human Rights Information Center.

"A number of upcoming sensitive events that will simultaneously take place on December 10, including Liu Xiaobo's Nobel Prize award, Hada's release, and the United Nations Human Rights Day celebration, are making the Chinese authorities extremely nervous," the group's Enghebatu Togochog told Reuters.

Last week, Chinese police prevented prominent artist Ai Weiwei from flying to South Korea on grounds of endangering state security, a move he called 'really silly'" and directly linked to the peace prize ceremony.

"It just shows the world that China does not respect its own laws," said Ai, one of China's most famous contemporary artists whose public comments, activities and art are some of the most flagrantly defiant and loudest forms of speech in China today.

Amnesty International estimates that more than 200 people have either been stopped from going abroad, detained or put under house arrest ahead of the ceremony.

DIPLOMATIC PRESSURE

The ceremony will be the first time that a laureate or his or her representative is not formally represented at the awards gala since Nazi Germany barred pacifist Carl von Ossietzky from going in 1935.

While some overseas Chinese dissidents have said they will attend, Beijing has pressured diplomats to boycott the ceremony, claiming the 'vast majority' of nations would do so.

The Norwegian award committee says two-thirds of those invited would attend.

China has denounced Liu's award as an 'obscenity' that should not have gone to a man it brands a criminal and subversive.

"The government seems genuinely to believe this Nobel Peace Prize is a global plot against China," said one China-based diplomat.

China feels hurt and misunderstood, seeing the award as a negation of the dramatic changes that have taken place since it decided to reform and open to the outside world in the late 1970s, said Victor Gao, director of the China National Association of International Studies.

"If anyone says that the Chinese people do not enjoy much, much greater human rights today compared with three decades ago, they are fooling themselves," Gao said.

"China actually considers itself to be a major force for peace in the world," he added.

Rights groups, though, say China's paranoia about Liu shows a deeper worry about the potential for the disgruntled and downtrodden to challenge Communist Party rule.

"Although Beijing tries to cast Liu Xiaobo as an unknown, isolated dissident, the Chinese leadership is well aware that Liu's ideas ... are not far removed from the common aspirations of ordinary Chinese people who want a government that at a minimum respect its own laws and allows a greater amount of press and internet freedom," said Nicholas Bequelin, a researcher who specializes in China for Human Rights Watch.

China will award its answer to the Nobel Peace Prize a day before it is bestowed on Liu, giving the newly created "Confucius Peace Prize" to a former Taiwan vice-president.