BEIJING, July 22 (Xinhua) -- The central parity rate of the yuan, China's currency Renminbi (RMB), weakened to 6.7859 per U.S. dollar Thursday from 6.7802 per U.S. dollar Wednesday, according to the data released by the China Foreign Exchange Trading System.

China's central bank announced on June 19 that it would further the reform of the formation mechanism of the yuan exchange rate to improve its flexibility.