The freeze-frame moment for Steven Spielberg came in one of those scripted, smiling meetings that Chinese officials act out so well.

The legendary director had come to Beijing hoping to use his moral influence to help end the killing in Darfur, where more than 200,000 people have died in a war between rebels and the Sudanese government, which is armed and financed by China.

He had offered to put his talents at the disposal of the Chinese to help them to stage memorable opening and closing ceremonies of the Olympic Games in August. It was an act of quiet diplomacy of the kind western leaders and businessmen insist works so well.

As Spielberg listened to the smooth words of his hosts, however, something sounded hollow. “It was a very rare chance to meet the Chinese leadership and Steven took it, gently arguing with many top Chinese politicians,” said a Hollywood executive who has talked to Spielberg about the encounter.

“But he could quickly tell they were merely being polite, and he equally politely avoided signing their contract, which might have prevented him from saying what he thought.”

Then the Chinese got persistent. “Officials kept bugging his office with e-mails, and after a while his assistants just stopped mentioning them,” the executive said.

Spielberg’s unease deepened after that. He had taken up the Olympic challenge for two reasons, friends say. One was his friendship with Zhang Yimou, the director of the hit film House of Flying Daggers, who is in charge of designing the opening and closing ceremonies. The other was the hope, “perhaps naive in retrospect”, the executive admitted, that he could change policy on Darfur from within China.

In America he was being attacked by the actress Mia Farrow and other Hollywood celebrities closely associated with the Darfur cause. She warned that he would become known as “the Leni Riefenstahl of the Beijing Olympics”, a reference to the German film-maker who chronicled the Berlin Games of 1936 at Adolf Hitler’s behest.

For the 61-year-old director the issue clarified itself over the Christmas holidays. “He knew he had gone as far as he could and a few weeks ago decided to announce his withdrawal on the fifth anniversary of the first Darfur tragedies,” the executive said.

Spielberg’s withdrawal on Tuesday was the latest beat in a drum roll of bad news for Beijing. Last month The Sunday Times revealed the cover-up of accidental deaths of workers building the iconic “bird’s nest” Olympic stadium. Then Prince Charles let it be known he would not be attending the Games and emphasised his personal admiration for the Tibetan spiritual leader, the Dalai Lama, who has called for peaceful protests during them.

The day after Spielberg’s withdrawal a letter came from a group of distinguished Nobel laureates and athletes to President Hu Jintao, calling on him to use his influence to end the conflict in Darfur.

All this was met with the standard repertoire of Communist party methods: flat denials, partial admissions, claims that the government was solving the problems and, when all else failed, abuse of any critics as enemies of the people. But Spielberg’s move was in a different league. Unequivocal, global in impact, it seemed to stun the Chinese leadership.

Now there are fears that his withdrawal may be followed by that of other western stars associated with the Games. There was speculation yesterday that the music producer Quincy Jones, who is writing the theme tune, might pull out.

A spokesman described the reports as “speculation” but added that Jones was “keeping an eye on the situation”.

What really worry the Chinese authorities are the growing calls for a boycott of the Games. A poll of nearly 2,500 people for The Sunday Times today shows strong support for Spielberg’s stand, with 49% saying they would back a boycott by British athletes, against 33% who said such a boycott would be wrong. The poll found that 75% thought Spielberg was right to pull out and just 12% thought he was wrong.

Now campaigners for a free Tibet, groups calling for religious freedom, grassroots democracy advocates, opponents of the death penalty and activists against environmental ruin are queuing up to embarrass the Chinese regime. How did it all go so wrong, so fast? THE news of Spielberg’s withdrawal was a bombshell for China. The country’s leadership, according to diplomats in Beijing, had been lulled into complacency by the politeness of visiting politicians, sports officials and businessmen, who never say anything unpleasant at those well-scripted meetings.

“Middle-ranking officials and those who know the outside world have been terrified because they know what’s coming,” said a diplomat who has discussed press coverage with the foreign ministry. “But this is China. They don’t dare tell the leaders.”

The Chinese appear genuinely to have believed that, because western diplomats thanked them for help on Sudan, Burma and North Korea, they could ignore the reality that a great deal of public opinion considered China’s actions inadequate or cynical.

Though they point to their support of the United Nations resolution that authorised increased foreign intervention in Darfur, the Chinese leadership will be looking for a way to ease the pressure on itself. While this will not involve a wholesale reappraisal of its relationship with Sudan, which provides 8% of its oil imports, a lower-level initiative is to be expected.

In Beijing there is a recognition that, given its increasing involvement in the global economy, China can no longer be seen to stand aloof from international political concerns.

John Ikenberry, professor of politics and international affairs at Princeton University, points out in the journal Foreign Affairs that while China “is well on its way to becoming a formidable global power . . . it not only needs continued access to the global capitalist system, it also wants the protections that the system’s rules and institutions provide”.

In other words, it has to be seen to obey the rules. The last thing it wants is to be seen as a bully like the world’s other “authoritarian-capitalist” power, Russia.

Mark Leonard, executive director of the European Council on Foreign Relations and author of the book What Does China Think? – to be published tomorrow – said: “While the glare of international publicity is there I think it will have an effect. China is very concerned about its international image. There is an obsession with not being seen as a threat and trying to be a soft power.”

Gordon Brown has yet to comment on Spielberg’s Olympic boycott, but behind the scenes those involved feel it may have helped to speed up the pace of diplomacy. Lord Malloch-Brown, the minister for Africa, said: “I have absolutely no doubt that what Spielberg did has made China and elsewhere sit up and take notice. It certainly had the effect of concentrating minds.”

Darfur is just one of a number of issues that will attract international attention – and protests – in the build-up to the Olympics.

When China was bidding for the Games seven years ago, Liu Jingmin, then vice-president of the bid committee, vowed that “by allowing Beijing to host the Games you will help the development of human rights”. For many it is an unfulfilled pledge.

Amnesty International UK plans protests drawing attention to repression and the extensive use of the death penalty in China. It says 8,000 prisoners may be executed every year. A mass demonstration and march on the Chinese embassy in London is timed for June 4, the 19th anniversary of the Tianan-men Square massacre of pro-democracy protesters.

The pressure on China will be nonstop until the Olympic flame is lit. When the torch relay comes to London in April on the way to Beijing, it will be shadowed by not one but two rival torches, one carried by the Dream for Darfur group, which will picket the relay as it travels across the world, and another by the Free Tibet Campaign.

“China should not be allowed to use its own Olympic torch to project a very misleading picture that everything is fine and normal in China and Tibet and drape itself in Olympic values of peace and universal fundamental principles when it is engaged in serious human rights abuses in Tibet,” said Matt Whitticase of the campaign.

Other activists believe targeting the Games’s corporate sponsors will have more effect. “Corporate sponsors are putting their reputations at risk unless they work to convince the Chinese government to uphold the human rights pledges it made to bring the Games to Beijing,” said Minky Worden, of Human Rights Watch.

Dream for Darfur plans to picket 19 companies associated with the Games, including Coca-Cola, McDonald’s, Visa and Panasonic, to highlight their “moral obligation” over Chinese actions in Africa.

Sponsorship experts are, however, sceptical about whether this will have any significant effect. “Sponsors walk into these things with their eyes wide open and think about the risks,” said one, whose clients include Olympic sponsors.

Nevertheless, the unexpectedly sudden intrusion of politics has troubled the sporting world. Athletes are typically indifferent to anything that distracts from their sporting achievements. But a few have spoken out on Darfur.

Richard Vaughan, Britain’s No 1 badminton player, has joined Team Darfur, a pressure group comprising more than 200 current and former athletes from 40 countries. About 10 British athletes, including Shelley Rudman, the Olympic bob skeleton silver medallist, and the skiier Noel Baxter are members of the group.

Vaughan, 29, from Cardiff, sees no sense in a boycott. “I think there’s a lot of good that can come from having the Games in China. It’ll open up China to lots of international influences, democracy and culture, which will hopefully be impossible for the Chinese government to stop. Lots of people say that communism ended after the [1980] Games in Moscow because it started a different way of thinking.”

That, perhaps, will be Beijing’s biggest concern.

Additional reporting: Dipesh Gadher and Jonathan Oliver

How politics have affected the Olympics

- Berlin 1936

Adolf Hitler saw the Games as a way to promote Nazi ideology. A magnificent new stadium, then the world’s biggest, was built and antisemitic posters around the city were removed. Jesse Owens, the black American athlete, turned Hitler’s notions of Aryan superiority on their head by winning four gold medals on the athletics track

- Mexico City 1968

Ten days before the opening ceremony, more than 250 pro-democracy demonstrators were killed by government troops in the Mexican capital. The Olympic authorities refused to act, calling it “an internal affair”. When, however, Tommie Smith and John Carlos, the American sprinters, raised their fists in a “black power” salute in the medal ceremony for the men’s 200 metres, they were sent home in disgrace

- Munich 1972

Palestinian terrorists from the Black September group took Israeli hostages in the Olympic village. In total 11 of the athletes and five terrorists were killed in a botched police raid. The Israeli security service Mossad then tracked down and killed many of those responsible for planning the attack, an operation depicted in Steven Spielberg’s film Munich

- Montreal 1976

In the first of three consecutive boycotts 22 African countries and Guyana refused to compete in protest at the International Olympic Committee’s refusal to ban New Zealand after its All Blacks rugby team had toured South Africa

- Moscow 1980

After the Soviet invasion of Afghanistan in 1979, the US led a 65-country boycott of the Moscow Games. Margaret Thatcher called for the British Olympic Association not to send a team, but it refused, saying individual athletes should decide. British athletes competed under the Olympic flag

- Los Angeles 1984

Inevitably, eastern bloc countries did not attend, citing fears about the security of their athletes. China, however, did compete, winning its first gold medal