Zhao Juan moves through the ballroom, resplendent in her newlywed's outfit of scarlet satin with gold embroidery. As she and her new husband greet the guests who've come to celebrate their wedding, they drink a toast at each table.

Then the bride reaches down, picks up a box of matches and lights a cigarette for every one of the male guests - and for some of the women too.

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It's a common scene at Shanghai weddings - and evidence of how deep a hold cigarettes have taken in Chinese culture. Smoking has been growing in popularity over the last 40 years and now two-thirds of Chinese men smoke. This is about the same level as Britain or America in the 1950s or 1960s, and as Sir Richard Peto of Oxford University puts it, "If the Chinese smoke like Americans, they die like Americans."

China's habit means it is heading fast towards a public health disaster. A massive study, coordinated by Sir Richard, suggested that a million Chinese men die prematurely every year of smoking-related diseases.

On present trends, that number will grow - with a third of all Chinese men meeting the same fate by the middle of the century.

Yang Bing-Hui of Zhongshan Hospital

At Shanghai's huge Zhongshan Hospital, that nightmare vision is already becoming reality. Zhang Jiancheng, a 66-year-old architect struggles for breath as he recalls his three decades of regular smoking. Now he's in deteriorating condition, suffering from serious chest disease brought on by smoking. The hospital's president, Professor Yang Bing-Hui, says that his doctors spend a third of their time dealing with these sort of smoking-related diseases.

The Chinese government has reacted by banning most cigarette advertising, restricting sales to minors and adding health warnings to packets. Shanghai is in the forefront of the anti-tobacco campaign and has prohibited smoking in many public places. The city has more than 140 non-smoking schools and even a non-smoking prison.

At Shanghai Medical University the authorities go even farther - administering a saliva test to find out whether new students are regular smokers. If the test is positive, they are strongly encouraged to kick the habit.

Shanghai Tobacco Corporation makes 80 billion cigarettes a year

However, some experts believe that the authorities could do more and point to a conflict of interest: the government campaigns against smoking but also owns the national tobacco monopoly. The company produces 95% of the cigarettes smoked in China and provides 10% of government revenue. Half a million people work in the cigarette manufacturing industry while 10 million farmers grow tobacco.

Meanwhile the foreign tobacco multinationals are eager to compete. Their imports and joint ventures are now comparatively small, but the companies anticipate full market access if China joins the World Trade Organisation.

"Japan Tobacco sees China very much the same way as most international manufacturers of fast-moving consumer goods will see China," says Axel Gietz of the Japanese cigarette giant, "as a huge market with incredible potential."

Chinese brands will need slick marketing to cope with foreign competition

This is a possibility that severely worries campaigners like Sir Richard Peto, who see a parallel with the former Warsaw Pact countries. The multinationals' aggressive marketing there has led to some of the world's highest smoking rates. There are fears that the same could happen in China - with women proving a particular target for the international manufacturers.

Fewer than one in twenty Chinese women smoke but there are indications that the rate is now rising, particularly among young women in big cities like Shanghai. Here, the traditional taboo against women smoking is breaking down.

"Young women are more open - they like to learn some more things, like smoking and dressing like Western girls," says one female guest at Zhao Juan's wedding. "They feel - well, it's the 21st century and everyone can smoke."

BBC Beijing correspondent Duncan Hewitt

Also in this week's Crossing Continents, Duncan Hewitt joins the worshippers enjoying China's religious revival and asks whether the country is experiencing a new openness about sex.