Film director Steven Spielberg has withdrawn as an artistic adviser to the Beijing Olympics.
The US director claimed his actions were a result of the Chinese government's refusal to condemn Sudan over the conflict in Darfur.
A statement from the Oscar-winner said: "I find my conscience will not allow me to continue business as usual.
"At this point, my time and energy must be spent not on Olympic ceremonies, but on doing all I can to help bring an end to the unspeakable crimes against humanity that continue to be committed in Darfur," he added.
Spielberg had previously raised concerns in a letter to Chinese president Hu Jintao last year.
China is a leading oil customer and supplier of weapons to Sudan and has received many critics for allegedly providing diplomatic cover to the country as efforts to send peacemakers into Darfur are continually rejected.
Spielberg's statement published in Variety yesterday added: "Sudan's government bears the bulk of the responsibility for these ongoing crimes, but the international community, and particularly China, should be doing more to end the continuing suffering there.
"China's economic, military and diplomatic ties to the government of Sudan continue to provide it with the opportunity and obligation to press for change."
Nine Nobel peace prize laureates, including Archbishop Desmond Tutu, Elie Wiesel and Jody Williams, also sent a letter to the Chinese president yesterday, calling for China to press Sudan into stopping the situation in Darfur.
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