The Chinese yuan has sunk to the lowest level since February 2011 after US Federal Reserve chief Janet Yellen said an interest rate hike in the next few months might be appropriate if economic data improves. 
Yellen's comments on Friday boosted the dollar against other major currencies. 
The central parity rate of the yuan on Monday weakened 294 basis points on Monday to 6.5784 against the dollar, according to the China Foreign Exchange Trading System. 
The central bank strictly controls yuan trading and sets a daily middle point from which the currency can trade up or down 2 per cent each day