China is hardly the first country to have seen the Olympics as an opportunity to impress the world. Nor is it the first Olympic host to discover that the floodlights of world attention illuminate not just achievements, but dark corners too. But this is a regime accustomed to keeping its critics under control, and it is only now beginning to realise what will hit it when the world flocks through its doors on its “lucky day” – 08.08.2008.

Seen from Beijing, China genuinely does have a great story to tell, of a nation whose wealth and prospects have changed beyond recognition in the space of a generation, and which is increasingly an engine of global growth. Beijing was braced for unwelcome criticism of its human rights record (and has been muzzling or locking up dissidents, the better to reduce the scope for what the authorities describe as prying into China’s business). It had, after all, told the IOC that hosting the Games would “help the development of human rights”.

The regime is also worried that no matter how many factories it closes down and car bans it imposes, the big Olympic story will be polluted skies and foetid water. It is concerned, most of all, that a “very small number” of protesters could “humiliate” China; it would take only a few pictures of the police beating up demonstrators to spoil the party. But it is safe to say that Beijing did not expect foreign policy to be its Achilles’ heel – least of all its policy towards Africa.

China’s attitude to Africa is straightforward, if unattractive: it is a 21st-century variant, economic rather than territorial, of the West’s “scramble for Africa”. The continent is rich in raw materials that China needs, just as it is poor in investment capital. To secure access to Africa’s natural wealth, China provides aid, arms, roads, railways and direct investment, without asking awkward questions. Sudan, which sells China two thirds of its oil output and is supplied by China with arms, is not the only ugly regime with which Beijing is happy to do business. It is one of the few countries still investing in Robert Mugabe’s Zimbabwe.

China has been under pressure for months to use its clout in Khartoum, but the incident that put it firmly on the spot took place on January 7, when the Sudanese armed forces attacked a UN convoy. In the Security Council debate that followed, China tried to shield Sudan from the consequences. Patience has snapped; not just in Hollywood but in the US Congress and in Africa, too – where China’s image will seriously be damaged by Archbishop Desmond Tutu’s signature this week on an open letter on Darfur to President Hu. Beijing may not like it; but it would be well advised not to ignore its Darfur critics. They will not go away until China becomes part of the solution, not a big part of the problem, in Sudan.

Times Recommends

• Red Cross: Israel guilty of 'unacceptable' conduct
• Mobster Gotti 'dipped neighbour in acid bath'
• Hollywood wakes up to the British breakfast