BEIJING (REUTERS) - China has set new targets for its provinces to reduce air pollution by 5 to 25 per cent, state media said on Tuesday, underscoring the government's concern about a source of public anger.

China regularly issues directives to try to tackle air pollution in major cities, but these have had limited effect.

Former health minister Chen Zhu said air pollution in the country causes premature deaths of 350,000 to 500,000 people yearly, state media reported on Tuesday. Mr Chen wrote the article in a December issue of the Lancet medical journal.

Air quality in large parts of northern and southern China reached unhealthy levels on Tuesday.

Under the new regulations, Beijing, its neighbouring city of Tianjin and northern Hebei province will have to cut the amount of PM 2.5 particles, which are especially bad for health, by 25 per cent annually, state news agency Xinhua said, citing the ministry of environmental protection.

China's commercial capital, Shanghai, the eastern provinces of Jiangsu, Zhejiang, Shandong and northern Shanxi will have to impose cuts of 20 per cent. Reductions of 15 per cent were set for Guangdong and Chongqing and 10 per cent for the Inner Mongolia Autonomous Region, Xinhua said.

The State Council, or cabinet, is mulling a system to evaluate each local government's progress and those who fail to reach goals will be "named and shamed", said the China Daily newspaper.

Air quality in cities is of increasing concern to China's stability-obsessed leaders, anxious to douse potential unrest as a more affluent urban population turns against a growth-at-all-costs economic model that has poisoned much of the country's air, water and soil.

Authorities have invested in various projects to fight pollution and empowered courts to mete out the death penalty in serious cases.

But enforcement of rules has been patchy at the local level, where authorities often rely on taxes paid by polluting industries.