China has rejected imports of some North Korean anthracite coal because the coal failed to meet domestic standards for mercury emissions, a local newspaper reported Wednesday, in what appeared to be China's first rejection of North Korean minerals over environmental concerns.

The shipment was returned to North Korea on Feb. 27 from the Rizhao port of China's northern coastal province of Shandong, the National Business Daily newspaper reported, citing an unnamed port official.

The report did not elaborate further, or include the volume of the rejected North Korean coal.

After three decades of rapid industrialization, China regularly sees hazardous air pollution with levels of particulate matter rising to nearly 40 times the limits set by the World Health Organization during the winter months.

In September, China announced strict regulations against the sale and import of coal with high toxic pollutants, including mercury and sulfur, to improve the country's air and water quality.

Anthracite coal accounted for 39.8 percent of North Korea's total exports to China last year.

In January, China's imports of North Korean coal plunged 53.2 percent from a year earlier to 16.78 million tons, according to Chinese customs data. (Yonhap)