BEIJING (Reuters) - China said on Wednesday that it will take measures to uphold the rights of Chinese companies, in response to the United States blacklisting companies and ships accused of breaking sanctions on North Korea. China has been fulfilling United Nations Security Council resolutions and opposes unilateral sanctions by any country, foreign ministry spokesman Zhao Lijian told a regular briefing. The U.S. has blacklisted six companies, including several based in China, and four ships accused of illicit exports of North Korean coal, the Treasury Department said on Tuesday.