Foreign Ministry spokeswoman Mao Ning said on Thursday that the United States' arbitrary seizure of a Russian-flagged tanker in the Atlantic Ocean constitutes a serious violation of international law.

"China has consistently opposed illegal, unilateral sanctions that lack a basis in international law and are imposed without authorization from the United Nations Security Council," Mao said.

She added that China firmly opposes any actions that violate the principles of the United Nations Charter and infringe upon the sovereignty and security of other countries.