Beijing reaffirmed its opposition to "long-arm jurisdiction" after Washington imposed sanctions on Tuesday against three Chinese companies and a Chinese individual for engaging in trade with Pyongyang.

"China has always strictly followed and implemented all United Nations Security Council resolutions, and our efforts are obvious to all," Foreign Ministry spokesman Lu Kang said on Wednesday.

In all, one person, 13 trading entities and 20 vessels from various countries were sanctioned by the US Treasury Department, it said on Tuesday. They are accused of engaging in trade with the Democratic People's Republic of Korea worth hundreds of millions of dollars, it said.