The News Agency of Nigeria reported that the CBN sold $263.67m at the previous WDAS on August 28.
Some dealers attributed the decrease in forex sales to the drop in oil price at the international market.
NAN also reported that the naira remained stable against the dollar, as it exchanged at N155.76, a rating it has maintained for five consecutive trading sessions.
The number of banks that participated at Monday’s auction was 20 against 18 at the previous auction, making it the highest since July 31.
Information from Punch was used in this report.