Two of China's largest aluminium smelters have been knocked out of action by a loss of power caused by "the most seriously freezing weather for the last 50 years" and damaged transmission lines in Guizhou province, according to the owner of both smelters Chalco.

The stricken smelters, Guizhou smelter and Zunyi Aluminium Company, had been forced to limit production due to general power and coal shortages in the province since last December.

But power lines knocked out by heavy snow had caused a complete stop in production since January 23.

The two plants produced 430,000 tonnes of aluminium last year, 15% of Chalco's output, around 3.5% of China's total alumium output.