The owners of steel mills in China are reported to be angry after Beijing imposed a surprise ban on coal imports from North Korea.

Analysts said the mills will be forced to buy more expensive domestic coal or seek alternative supplies from Russia or Australia, increasing their costs.

While North Korea accounts for only a small portion of China’s total coal imports, it is the main foreign supplier of anthracite, which is used to make coke.

A steel-mill purchasing manager, based in the northern province of Liaoning, said: “This news really took us by surprise. We are looking at a couple of alternative plans. These might include buying anthracite from Shanxi province or buying more coke from local providers, but both are more costly.”

His firm has been using about 10,000 tonnes of North Korean anthracite each month.