Beijing has stepped up its warnings against the U.S. by cautioning about working, studying and traveling in America.

China's Ministry of Foreign Affairs announced a safety warning on Tuesday for Chinese citizens and companies in the U.S.. according to state broadcaster CCTV.

"Recently, U.S. law enforcement agencies have on multiple occasions used methods such as entry and exit checks, and on-site interviews to harass Chinese citizens in the U.S.," the ministry said, according to CCTV.

"The Foreign Ministry and the Chinese Embassy and Consulate in the U.S. warn Chinese citizens and Chinese-invested institutions to raise their safety awareness, strengthen preventative measures, and respond properly," it added.