China's railway authority has drawn up plans to guarantee the supply of coal to power plants over coming months as the country's worst electricity shortages in years kicks in.

"The Ministry of Railways has already implemented related measures and made related adjustments to guarantee the supply of coal to major regions," it said in a statement.

The ministry said it would "ensure that rail transportation problems do not cause power restrictions", and would see to it that coal was delivered to regions where inventories were currently low.

The statement said railways delivered an average of 87,423 shipments of coal per day from May 1-23, and the 363 power plants directly supplied by the ministry had 31.66 million tonnes of stockpiles, which could last 13.9 days.

State Grid Corp, China's biggest power distributor, said during a meeting on Monday that the country could be facing its worst supply crunch ever, with capacity shortages expected to hit 30-40 gigawatts during the summer consumption peak.

Power shortages have usually been blamed on an electricity pricing system that does not allow utilities to pass rising fuel costs onto consumers, but transportation bottlenecks have also had a considerable impact in previous years.

China's overloaded rail and road networks struggle to deliver vast quantities of coal from major producing regions in the north to big electricity-consuming provinces such as Jiangsu, Zhejiang and Guangdong in the east and southeast, where local supplies are scarce. (Reuters)