China's December coal output climbed 2.1 percent from the year before, government data showed, hitting the highest level in over three years as major miners ramped up production amid robust winter demand and after the country started up new mines, Reuters reported.
Miners produced 320.38 Mt (353.15 million st) of coal in December, according to data released by the National Bureau of Statistics. That is the largest volume since June, 2015.
China approved more than $6.64 billion worth of new coal mining projects last year, much more than 2017, official documents show.
That came after the country closed old and more-polluting coal mines as part of its battle to clean up the environment.
The new projects stoked overall coal output last year, with annual production rising 5.2 percent to the highest since 2015 at 3.55 Gt (3.91 billion st).
However, some miners and traders expect supplies to fall sharply in January following a crackdown on coal mines after a major accident on Jan. 13 in the northwestern province of Shaanxi, potentially dragging on output through the year.
"It is now possible that Shaanxi will implement the strictest-ever regulations on illegal production, which would significantly reduce output in the province for the year," Zhai Yu, senior consultant at analysts Wood Mackenzie said in a note published in January.
"If stricter checks are extended to other provinces, domestic supply could tighten from its currently relaxed situation, helping coal imports as a result," Zhai wrote.
Shaanxi accounts for about 20 percent of China's annual coal production.