China has just 12 days of coal reserves left at most of its power stations, after the end of a cold and stormy winter

According to a report in New Scientist, some provinces, including Hebei, bordering Beijing, have less than a week's coal left. This is a record low, the state electricity regulatory commission revealed.

Coal imports, which started last year, have also failed to meet the difference between supply and demand. Such is the demand for power from an economy that has been growing by 10% a year for more than two decades.

China relies on burning coal for 70% of its electricity. Even though Chinese coal production in the first quarter of this year was up almost 15% on the same period last year, it has apparently not been enough to meet the rapidly growing demand.

According to the deputy head of the Chinese electricity regulatory commission, Wang Yeping, the country is likely to be short of 10 gigawatts of electricity generating capacity by this summer.

That will cause brownouts and power shortages, particularly in southern provinces such as Guangdong, where the spread of air conditioning systems is competing with industry for power.

The coal mining industry and the rail network needed to bring the coal to the power plants are both struggling to keep up with the drive to build ever more generating capacity.

The strains also raise questions about how much longer China's breakneck industrialisation can continue.