China has criticized U.S. sanctions against a state-run weapons supplier for exporting missiles.
Chinese authorities have rejected Washington's accusation that it violated efforts to stop the proliferation of weapons of mass destruction.
The United States has imposed sanctions on China New Era, a state-run company that Washington says engaged in activities aiding the proliferation of missile technology. The sanctions mean the U.S. government will not do business with the company nor allow it to export goods to the United States.
China New Era handles exports for Chinese military contractors.
Chinese Foreign Ministry spokesman Kong Quan said Thursday that Beijing has been strict in enforcing non-proliferation rules.
Mr. Kong says that once Chinese officials detect such activities, they are immediately investigated and stopped.
Mr. Kong demanded that Washington withdraw its sanctions.
The United States did not say what country received the missile technology from China New Era. News reports from Washington, however, quoted unnamed sources as saying that the buyer was Iran.
This is the 11th time the United States has penalized Chinese companies for violating international restrictions on trade in missile technology.
Also on Thursday, officials in Beijing warned the United States not to block imports of Chinese textiles after an agreement imposing quotas on the global textile trade expire.
China says such a move could hurt the confidence of its companies and the global trade environment.
U.S. textile companies are pushing Washington to limit Chinese imports, fearing they will surge after the global textile agreement expires at the end of this year.