About 3.33 million hectares (8 million acres) of China's farmland is too polluted to grow crops, a government official said on Monday, highlighting the risk facing agriculture after three decades of rapid industrial growth.

 

China has been under pressure to improve its urban environment following a spate of pollution scares.

 

But cleaning up rural regions could be an even bigger challenge as the government tries to reverse damage done by years of urban and industrial encroachment and ensure food supplies for a growing population.

 

The area of China's contaminated land is about the same size as Belgium. No more planting would be allowed on it as the government is determined to prevent toxic metals entering the food chain.

 

This year, inspectors found dangerous levels of cadmium in rice sold in the southern city of Guangzhou. The rice was grown in Henan, a major heavy metal-producing region.

 

China's determination to squeeze as much food and resources as possible from its land has thousands of farms close to chemical plants, mines and other heavy industries, raising the risks of contamination.

 

With food security still the most pressing concern, China is determined to ensure that at least 120 million hectares (295 million acres) of land is reserved for agriculture, a policy known as the "red line". The rehabilitation of polluted land is part of that policy.

 

A government land survey revealed traces of toxic metals dating back at least a century as well as pesticides banned in the 1980s, and state researchers have said that as much as 70 per cent of China's soil could have problems.