US Treasury Secretary Jacob Lew on Friday told his Chinese counterpart at a G20 meeting in Ankara to avoid competitive devaluation and improve communication of economic policy.

"China should... refrain from competitive devaluation," a US Treasury spokesperson quoted Lew as telling Chinese Finance Minister Lou Jiwei in a meeting on the sidelines of the G20, adding Lew also "underscored the importance of China carefully communicating its policy intentions and actions to financial markets".

The Chinese central bank on August 11 devalued the yuan by nearly two percent, surprising markets and raising concerns about the effects of China's economic slowdown.