China's northern province of Shanxi produced 15.2 percent less coal in the January-November period than last year.
In the 11 months, output totaled 738 million tonnes, the provincial bureau of statistics said Sunday.
In November alone, the output declined 9.4 percent year on year to 74.9 million tonnes, it said.
From April, mines in Shanxi started to limit production to 276 working days a year, 84 percent capacity. Uncertificated mines were closed.
Since 2012, demand for coal has been slowing. China set a target of cutting coal capacity by 250 million tonnes in 2016 to revive the industry. The decline in output caused a 60 percent rise in coal prices this year.
Shanxi shut down 25 coal mines this year with a total capacity of 23.3 million tonnes by the end of October.
