By Francis Markus BBC correspondent in Shanghai

Under an international treaty which China signed in New York earlier this week, the warnings are expected to cover at least 30% of the printed surface of the packet.

A quarter of China's population smokes

It is not yet clear how soon China will ratify the treaty. Only a handful of signatories have already done so.

Even when it does, with over 350 million Chinese, or a quarter of the population, smoking, cutting the human cost of China's tobacco habit will be a huge task.

China's love affair with the cigarette is in evidence wherever you go - restaurants hazy with smoke, people, almost always men, puffing away on rural buses.

And anti-smoking advocates say the problem is getting worse.

Now though, the country is at least preparing to take measures bringing it into line with commitments by dozens of other states.

Earlier this week Beijing signed up to an international treaty, concluded this year, called the Framework Convention on Tobacco Control.

Under its provisions, China will have to increase dramatically the size of health warnings on cigarette packets, currently quite low key, and curb tobacco advertising.

At least 2,000 people die from tobacco-related illness each day in China and official media say the number could quadruple by 2050.

Meanwhile, the state-dominated domestic tobacco industry provides a vital source of tax revenue, and the Western tobacco giants are jostling to expand their market share in China.