BEIJING - The Chinese currency Renminbi, or the yuan, strengthened 55 basis points to 6.4386 per US dollar on Thursday, the highest since China started the exchange rate reform six years ago, according to the China Foreign Exchange Trading system.

In China's foreign exchange spot market, the yuan is allowed to rise or fall by 0.5 percent from the central parity rate each trading day.

The central parity rate of the yuan against the US dollar is based on a weighted average of prices before the opening of the market each business day.