HANOI, May 28 (Xinhua) -- Vietnam's central bank on Monday adjusted up its reference exchange rate between Vietnamese dong and U.S. dollar by 7 Vietnamese dong to 22,596 Vietnamese dong per U.S. dollar.

With the current trade band of plus or minus 3 percent, the ceiling exchange rate is 23,273 Vietnamese dong per U.S. dollar, and the floor rate is 21,918 Vietnamese dong per U.S. dollar, said the State Bank of Vietnam.

Meanwhile, listed rates at big commercial banks in Vietnam went up significantly. BIDV raised both rates by 20 Vietnamese dong, buying the greenback at 22,760 Vietnamese dong per U.S. dollar and selling at 22,830 Vietnamese dong per U.S. dollar. Rates at Vietcombank advanced by 10 Vietnamese dong to 22,755 Vietnamese dong per U.S. dollar for buying and 22,825 Vietnamese dong per U.S. dollar for selling.

Last week, the reference exchange rates saw two ups and one down with total magnitude of 10 Vietnamese dong and 11 Vietnamese dong, respectively.

According to Vietnam's National Financial Supervisory Commission, the central exchange rate in late 2017 rose around 1.6 percent against early 2017, while the average rate offered by commercial banks decreased 0.2 percent, and on the free market dropped some 1.5 percent.