On Monday morning, the State Bank of Vietnam (SBV) raised the reference price for $1 to VND23,069, an increase of VND15 from the previous day, up VND73 from one month ago.

This represented a VND244 rise since the beginning of the year, or a 1.06 percent increase.

Commercial banks were quick to follow. Vietcombank raised its buy price to VND23,365 and selling price to VND23,485, up VND25 from the end of last week and surpassing the bank’s last peak in early May.

The difference between buying and selling prices was kept at VND120 per dollar.

VietinBank used the same rates for the greenback this morning. Eximbank, Techcombank and Sacombank lowered their buy-sell rates to VND23,470-23,480.

On the free market, prices have risen by around VN20-30 since the end of last week, from VND23,430 to VND23,450 on average.

In its recent report, the analytics division of securities firm Saigon Securities Incorporation, SSI Research, said that the U.S.'s first quarter GDP growth of 3.2 percent, exceeding forecasts, has caused the dollar to rise sharply.

The U.S. Dollar Index (DXY), which measures the strength of the greenback against a basket of other currencies, passed the 98 mark (98.02 points) this morning, and is approaching its 2019 high of 98.2 points on April 25.

"International developments, along with the sudden narrowing of the VND-dollar interest rate gap on the interbank market had a strong impact on market sentiment, causing the USD/VND exchange rate to rise for both banks and the free market," SSI Research said.

In last week's report, securities firm Bao Viet Securities (BVSC) had said that strong and unpredictable movements in the foreign exchange market were the result of escalating trade tensions between the U.S. and China.

"The SBV will continue to slightly depreciate the dong to create room for sudden changes in the global market," it said.

BVSC also said that the USD/VND exchange rate is likely to fluctuate in the range of 2 percent this year, a band authorities have allowed in previous years.