The wife of jailed Nobel Peace Prize winner Liu Xiaobo has invited dozens of Chinese activists and luminaries to go to the Nobel award ceremony in Oslo on her behalf because mainland authorities are likely to block her from going.

Liu Xia said in an open letter posted online that she believed her husband would want his friends "to attend this historic ceremony and to share the glory."

Currently unreachable because she is under house arrest, Liu Xia said in the letter that the likelihood of her or her jailed husband being allowed to go to Norway for the December 10 event was slim. Liu Xiaobo, a writer and outspoken government critic, is serving an 11-year jail term for inciting subversion with Charter 08, a bold call for sweeping political reforms that he co-authored.

Numerous international rights groups have called for his release. On Monday, a group of 15 Nobel Peace Prize winners including the Dalai Lama, Desmond Tutu and former US President Jimmy Carter issued a letter urging world leaders who will attend the G-20 Summit in South Korea next month to raise Liu's case with Chinese President Hu Jintao during the event.

China's government has reacted angrily to the award, calling it a gross interference in its internal affairs. Liu Xia's invitation letter lists 143 people, many of them well-known Chinese activists such as Ding Zilin, whose teenage son was killed during the military crackdown against pro-democracy protests around Tiananmen Square in 1989, and Li Rui, the former secretary to revolutionary leader Mao Zedong and an outspoken supporter of democratic reform.

Many of the invitees are frequently placed under house arrest during sensitive periods or are under constant surveillance by security officials, making it unlikely that they would be allowed to leave the country.

One invited guest, rights lawyer Gao Zhisheng, disappeared in April shortly after announcing he was abandoning his role as a government critic. His family says they have no idea what has happened to him.

Also invited are numerous Chinese celebrities, including film director Chen Kaige, actor Jiang Wen, singer and race car driver Han Han and author Wang Shuo. Liu Xia said in the letter that she had invited prominent cultural figures because she hoped they could help promote social change in China.

"China's social progress needs the joint effort of people from all walks of life," she wrote. The letter is dated October 20 but was not posted online until Monday.

Yang Jianli, an exiled Chinese democracy activist and close friend of the couple, confirmed on Tuesday from his home in Brookline, Massachusetts, that the letter was authentic and said Liu Xia asked him to help coordinate the event.

Yang said more than a dozen people had already responded via email, saying they hope to attend. When a list is finalised, Yang will give it to the Nobel Committee, which, he said, has agreed to issue invitation letters to help guests obtain travel visas to Norway.

"This is a very rare opportunity for so many people to converge to the same place with the same goal," Yang said. "I think I have to make good use of this opportunity to make it a moment of unifying and looking to the future."

Yang said that despite his excitement about bringing people together, the event was tainted by the fact that Liu himself remains in prison. "We can't forget that our real, real hero, Liu Xiaobo, is still languishing in prison, and his wife is under house arrest," he said.

One of the invitees, Beijing lawyer Pu Zhiqiang, said Monday he had heard about the letter but had not yet seen it for himself. "If I am able to go, I think it would be a wonderful thing," he said.