China has expressed strong opposition and lodged solemn representations with the U.S. for putting five Chinese firms on its trade blacklist for allegedly supporting Russia's military, Chinese Foreign Ministry spokesperson Zhao Lijian said at a news conference on Wednesday. 

The trade cooperation between China and Russia is based on mutual respect and equality, the spokesperson said, adding that it should be free of any third-party interference.

China urges the U.S. to revoke its decision and stop its long-arm jurisdiction or unilateral sanctions against China, Zhao said.

China will take all necessary measures to safeguard the legitimate rights of Chinese companies, he said.

The five Chinese companies are Connec Electronic Ltd., World Jetta, Logistics Limited, King Pai Technology Co., Ltd. and Winninc Electronic.

The firms' blacklisting means their U.S. suppliers need a Commerce Department license before they can ship items to them.

The U.S. Commerce Department also added another 31 entities to the blacklist from countries that include Russia, UAE, Lithuania, Pakistan, Singapore, the United Kingdom, Uzbekistan and Vietnam, according to the Federal Register entry. 

(With input from Reuters)