The report, produced in co-operation with Chinese government ministries over several years, found about 750,000 people die prematurely in China each year, mainly from air pollution in large cities.

China’s State Environment Protection Agency (Sepa) and health ministry asked the World Bank to cut the calculations of premature deaths from the report when a draft was finished last year, according to Bank advisers and Chinese officials.

Advisers to the research team said ministries told them this information, including a detailed map showing which parts of the country suffered the most deaths, was too sensitive.

“The World Bank was told that it could not publish this information. It was too sensitive and could cause social unrest,” one adviser to the study told the Financial Times.

Sixteen of the world’s 20 most polluted cities are in China, according to previous World Bank research.

Guo Xiaomin, a retired Sepa official who co-ordinated the Chinese research team, said some material was omitted from the pollution report because of concerns that the methodology was unreliable. But he also said such information on premature deaths “could cause misunderstanding”.

“We did not announce these figures. We did not want to make this report too thick,” he said in an interview.

The pared-down report, “Cost of Pollution in China”, has yet to be officially launched but a version, which can be downloaded from the internet was released at a conference in Beijing in March.

Missing from this report are the research project’s findings that high air-pollution levels in Chinese cities is leading to the premature deaths of 350,000-400,000 people each year. A further 300,000 people die prematurely each year from exposure to poor air indoors, according to advisers, but little discussion of this issue survived in the report because it was outside the ambit of the Chinese ministries which sponsored the research.

Another 60,000-odd premature deaths were attributable to poor-quality water, largely in the countryside, from severe diarrhoea, and stomach, liver and bladder cancers.

The mortality information was “reluctantly” excised by the World Bank from the published report, according to advisers to the research project.

Sepa and the health ministry declined to comment. The World Bank said that the findings of the report were still being discussed with the government.

A spokesperson said: “The conference version of the report did not include some of the issues still under discussion.” She said the findings of the report were due to be released as a series of papers soon.