The bank offered $40 million at the sale and said it had sold $38.4 million at a cut-off price of 7.1401 pounds to the dollar, a rate unchanged from its last sale on Sunday.
The rates at which banks are allowed to trade dollars are determined by the results of central bank sales, giving the bank effective control over official exchange rates.
In the unofficial market, a trader said the pound was trading at 7.80 to the dollar on Monday, virtually unchanged from Sunday when traders put it at 7.80/81.