SHANGHAI, July 22 (Reuters) - China's central bank on Thursday set its official yuan midpoint at the firmest level in a week, lifting its value against its major trading partners to a new more than five-year high.

The People's Bank of China (PBOC) set the midpoint at 6.4651 yuan per dollar prior to the market open, 184 pips or 0.28%, stronger than the previous fix of 6.4835. It was the firmest since July 15.

And the strengthened official guidance rate has pushed China's trade-weighted yuan basket index to 98.77, the highest since March 15, 2016, up 4.15% so far this year, according to Reuters' calculations based on official data.

(Reporting by Winni Zhou and Andrew Galbraith; Editing by Jacqueline Wong)