China has expressed regret over film director Steven Spielberg's decision to pull out as artistic adviser to the Beijing Olympics over the Darfur issue.
Mr Spielberg's decision is a high-profile blow to Olympic organisers
The foreign ministry said "ulterior motives" may be behind criticism of its links with Sudan.
The director said his conscience would not allow him to continue in his role.
China has strong economic and military ties with Sudan, which campaigners say it should use to put pressure on Khartoum to resolve the Darfur crisis.
A UK newspaper has published a letter from 80 Nobel laureates and artists urging Beijing to help end the conflict.
Chinese foreign ministry spokesman Liu Jianchao said: "We have taken notice that recently there have been many controversies and actions involving China and Darfur.
"It is understandable if some people do not understand the Chinese government policy on Darfur, but I am afraid that some people may have ulterior motives, and this we cannot accept," he told a news conference.
"China is also concerned about the humanitarian situation in Darfur. [But] empty rhetoric will not help. We hope that relevant people will be more pragmatic."
Beijing says it has appointed a special envoy to Darfur and sent peacekeepers to the region. But many, including Steven Spielberg, say that is not enough.
At least 200,000 people have died and two million forced from their homes in the five-year conflict in Sudan's Darfur region, where pro-government militia are accused of widespread atrocities.
Sudan denies backing the Janjaweed militia and says the suffering in Darfur has been exaggerated.
Sudan sells some two-thirds of its oil to Beijing, while Beijing sells weapons to the Sudanese government and has blocked efforts to pressure Khartoum in the UN Security Council.
Campaigners say arms sold by China to the Sudanese government that have been used in Darfur.
Mr Spielberg's announcement late on Tuesday is Beijing's first big setback in staging the Olympics, analysts say.
The renowned director, who had been brought in as artistic adviser for the opening and closing ceremonies of the Games, said his conscience would not allow him to continue in the role.
HAVE YOUR SAY
The real question is why the Olympics were awarded to China in the first place
"Sudan's government bears the bulk of the responsibility for these ongoing crimes, but the international community, and particularly China, should be doing more," he said.
Adding to the pressure, British newspaper the Independent has published on its front page the full text of a letter signed by 80 Nobel laureates, politicians and artists to Chinese President Hu Jintao urging greater action on Darfur.
Signatories include South Africa's Archbishop Desmond Tutu, US former Senator Bill Frist and British playwright Tom Stoppard, as well as a host of former Olympians.
The letter, released by campaigning group Crisis Action on 12 February, said China had both the opportunity and the responsibility to help bring peace to the troubled region.
"Ongoing failure to rise to this responsibility amounts, in our view, to support for a government that continues to carry out atrocities against its own people," the letter said.