Rebel groups in Darfur praised the decision by film director Steven Spielberg to quit as an artistic adviser to the 2008 Olympics, but there was no reaction from the Games organisers in Beijing on Wednesday.
Spielberg said he was withdrawing his services because of China's policy on the conflict in Sudan's Darfur region.
His conscience would not allow him to continue his work on the opening and closing ceremonies for the August 8-24 Games while "unspeakable crimes" continued to be committed in Darfur.
Darfur's splintered rebel groups said Spielberg's move could shame Beijing, a major investor in Sudan's oil industry and the East African country's largest supplier of weapons, into changing its stance on the region.
"This will send a message to other countries, other individuals and athletes, who haven't taken a strong stance on Darfur up to now," said spokesman for the insurgent Justice and Equality Movement (JEM) Ahmed Hussein Adam.
"We are calling on all countries to boycott the Olympics, athletes as well."
Some 200,000 people have died and 2.5 million have been driven from their homes in more than four years of conflict in Sudan's western region of Darfur, according to estimates by international experts. Khartoum puts the death toll at 9,000.
China is accused by critics of providing diplomatic cover as Khartoum stonewalls efforts to send peacekeepers into Darfur.
A spokesman for the Beijing Organising Committee for the Olympic Games (BOCOG) said no reaction to Spielberg's move was expected on Wednesday.
"His decision is a personal one," an International Olympic Committee (IOC) official told Reuters.
"The IOC has not been part of the relationship between Spielberg and the Games' organisers. It is not for the IOC to make a particular comment."
Spielberg's statement was released on the day that nine Nobel Peace laureates - including Archbishop Desmond Tutu, Elie Wiesel and Jody Williams - sent a letter to President Hu Jintao urging a change in China's policy toward its ally Sudan.
He sent his own letter to Hu in April after actor and Darfur activist Mia Farrow said he risked becoming to the Beijing Games what Nazi propagandist Leni Riefenstahl was to the 1936 Berlin Olympics.
New York-based watchdog Human Rights Watch said Spielberg's withdrawal should prompt other influential outsiders, such as governments, corporate sponsors and National Olympic Committees to press Beijing for reform.
"These influential players should be prepared to show the steps they are taking to address the worsening rights climate in China, or they risk being tarnished by a human rights debacle," Minky Worden, the pressure group's media director, said in a statement.
The Chinese government has rejected attempts to influence their foreign and domestic policy by leveraging the Beijing Games. They accuse their critics of going against the spirit of the Olympic movement by "politicising" a sporting event.
More than 30,000 international media are expected to descend on the Chinese capital for the August 8-24 Games, intensifying scrutiny on the government and its human rights record.
On the streets of Beijing on Wednesday, opinion was firmly against the film director.
A student surnamed Nie accused him of being "childish" while a freelancer surnamed Wu blamed "biased" reports on China's attitudes to international situations.
"There is no need for China to pay the bill for the human rights conditions of any other country," said a 27-year-old surnamed Mao.
"I think the Chinese government... will choose a good Chinese director who can also give guidance to the opening ceremony of the Olympics." (Reuters)
Olympics-Darfur rebels praise Spielberg, Beijing silent