The United States said on Monday it will start treating four major Chinese media outlets as foreign embassies, alleging they are mouthpieces for Beijing, in a move that is likely to further sour already fraught ties between the world's top two economies.

David Stilwell, the senior US diplomat for East Asia, told reporters the designation would affect China Central Television, the China News Service, the People's Daily and the Global Times, and reflected their real status as "propaganda outlets" under the control of the Chinese Communist Party...