Chinese foreign ministry spokeswoman Hua Chunying told reporters at a regular briefing that China opposes unilateral sanctions and "the long-arm jurisdiction taken'' by US against Chinese entities and individuals.

Among those sanctioned are six Chinese companies, including three coal companies.

Hua said Chinese authorities will follow their own regulations and laws to investigate and punish if necessary the companies in question.

China has been "earnestly and comprehensively'' implementing the UN Security Council sanctions on North Korea, and "our efforts are there for all to see,'' Hua said. Washington says its own sanctions are intended to complement the UN ones, including the latest ones which were imposed after North Korea tested two intercontinental ballistic missiles last month that may be able to reach parts of US.