HANOI, July 5 (Xinhua) -- Vietnam's central bank on Thursday raised up its reference exchange rate between Vietnamese dong and U.S. dollar by 8 Vietnamese dong to 22,638 Vietnamese dong per U.S. dollar.

With the current trading band of plus or minus 3 percent, the ceiling exchange rate is 23,317 Vietnamese dong per U.S. dollar, and the floor rate is 21,959 Vietnamese dong per U.S. dollar, said the State Bank of Vietnam.

Meanwhile, listed rates at big commercial banks in Vietnam went down slightly. Vietcombank cut both rates by 5 Vietnamese dong, buying the greenback at 22,995 Vietnamese dong per U.S. dollar and selling at 23,065 Vietnamese dong per U.S. dollar.

Rates at BIDV remained unchanged at 23,000 Vietnamese dong per U.S. dollar for buying and 23,070Vietnamese dong per U.S. dollar for selling.

This week, the reference exchange rates have seen one up and two downs with total magnitude of 8 Vietnamese dong and 20 Vietnamese dong, respectively.

According to the central bank, as of June 11, the reference exchange rate rose 0.63 percent against the end of 2017, while the average rate offered by commercial banks advanced 0.47 percent.