The action was interpreted as a sign from China in support of US- led sanctions, which were mounted to curtail North Korea's arms trafficking in response to its May 25 nuclear test.

The tightened sanctions are considered relatively ineffective without Chinese participation. China is a major source of trade cash, energy and food for North Korea.

The action comes amid a UN-led call on China to tighten control of trafficking into North Korea to implement the tightened sanctions.