Leading article: An overdue debate about the Beijing Olympics

One not unreasonable response to Steven Spielberg's decision to resign as artistic adviser to the Beijing Olympic Games would be to ask why he offered his services in the first place. Of course, China is an exciting place. Equally exciting is the challenge represented by the world's most populous nation and fastest-growing economy hosting the world's premier sporting event. But any global figure runs a risk if he lends his name to the Chinese government.

Mr Spielberg has now – quite rightly – decided that the liabilities outweigh the advantages. In his statement, he said that his conscience would not allow him to continue with "business as usual" and he would now concentrate on trying to halt the "unspeakable crimes against humanity... in Darfur." While conceding that Sudan bore most responsibility, he insisted that "the international community, and particularly China" should be doing more to end the suffering.

For the Chinese, this is an enormous setback, if not quite a humiliation. You can accuse Mr Spielberg of arrogance in effectively elevating his own influence to the level of that of the Chinese government. But such an assumption is not completely delusional. As the subsequent headlines showed, Steven Spielberg's name and standing resonate around the globe. Rightly or wrongly, what he says about politics carries the imprimatur of his reputation as a film-maker of tremendous moral force.

The Beijing government had been hoping – as so many governments with dubious records have hoped before – that it could keep sport and politics in separate compartments. It had done its utmost to prevent its role as host of the Olympics becoming embroiled in politics and, until this week, it had been successful. Or, to put it slightly differently, other governments, sporting bodies and influential individuals had been remarkably supine in allowing Beijing to preserve the distinction.

It is true that the Chinese had thrown out a few concessions to keep its critics at bay. Foreign journalists have been allowed to travel the country without special permission. Detained government critics have sooner or later been released. And earlier interventions by Mr Spielberg prompted China to send a special envoy to Darfur, to send 300 military engineers to the region to help keep the peace, and to contribute medical assistance. This is probably more than China would have done without Mr Spielberg's representations.

At the same time, however, it is disappointing that the director, like so many other international luminaries, appears to limit his differences with China to the issue of Darfur. As he himself notes in his statement, China may be complicit in the atrocities in that region, but it does not bear primary responsibility. There are, however, many other areas much closer to home for which the Chinese government is directly responsible.

Such elementary rights as freedom of speech, assembly and belief are regularly violated in China. Journalists, academics, religious, trade union and environmental activists are routinely detained, even if – in this Olympic year – they are released when an international outcry threatens. Pity those who have no one to speak for them. China has a prison system no less remote and inhumane than the former Soviet gulag. The internet is censored. The treatment of Tibet is an abiding disgrace. China is not, by a long way, a democratic country.

Darfur is a cause that has rallied the stars and it deserves all the publicity it receives. But if Steven Spielberg's break with Beijing coincidentally opens up a wider debate about rights inside China, he will have done the world a favour. The Olympics offer Beijing an unrivalled showcase for its success; it must expect much closer outside scrutiny in return.