Vietnam's central bank on Monday adjusted up its reference exchange rate between Vietnamese dong and U.S. dollar by nine Vietnamese dong to 22,567 Vietnamese dong per U.S. dollar.

With the current trading band of plus or minus 3 percent, the ceiling exchange rate is 23,244 Vietnamese dong per U.S. dollar, and the floor rate is 21,890 Vietnamese dong per U.S. dollar, said the State Bank of Vietnam.

Meanwhile, listed rates at big commercial banks in Vietnam were adjusted differently. BIDV raised both rates by five Vietnamese dong to 22,765 Vietnamese dong per U.S. dollar for buying and 22,835 Vietnamese dong per U.S. dollar for selling.

Vietcombank cut the buying rate by 15 Vietnamese dong to 22,765 Vietnamese dong per U.S. dollar and the selling rate by 35 Vietnamese dong to 22,835 Vietnamese dong per U.S. dollar.

Last week, the reference exchange rates saw one up and three downs with total magnitude of five 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.