The median overnight interbank rate on Egypt's pound slipped to about 9.06 percent on Sunday from 9.161 percent on Thursday after the central bank cancelled two treasury bill auctions at short notice.
Bankers said the rates were also low because the central bank's two-week period for calculating bank reserves ends on Monday and rates usually fall as banks square their books.
Nine percent is the lower limit for overnight rates, set by the central bank by guaranteeing to take deposits at that rate.
Three out of seven banks contacted by Reuters dealt overnight money at rates of between 9.05 and 9.1 percent, compared with a range of 9.125 to 9.3 percent on Thursday.
One of the banks dealt 10-day money at 9.25 percent. On Thursday banks dealt one-week money at rates between 9.18 and 9.5 percent.
On the foreign exchange market, the pound strengthened to 5.7588 pounds to the dollar at 1200 GMT, from Thursday's closing weighted average of 5.7594.