HANOI, June 12 (Xinhua) -- Vietnam's central bank on Tuesday adjusted up its reference exchange rate between Vietnamese dong and U.S. dollar by 8 Vietnamese dong to 22,575 Vietnamese dong per U.S. dollar.

With the current trading band of plus or minus 3 percent, the ceiling exchange rate is 23,252 Vietnamese dong per U.S. dollar, and the floor rate is 21,898 Vietnamese dong per U.S. dollar, said the State Bank of Vietnam.

Meanwhile, listed rates at big commercial banks in Vietnam were adjusted differently. Bank for Investment Development of Vietnam raised both rates by 5 Vietnamese dong, buying the greenback at 22,770 Vietnamese dong per U.S. dollar and selling at 22,840 Vietnamese dong per U.S. dollar.

Vietcombank kept both rates unchanged at 22,765 Vietnamese dong per U.S. dollar for buying and 22,835 Vietnamese dong per U.S. dollar for selling.

Last week, the reference exchange rates saw one up and three downs with total magnitude of 5 Vietnamese dong and 13 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.