The traders said banks were in little need of pounds after squaring their positions last week according to the requirements of the two-week period, which ends on Monday. A new period begins the following day.
"It's very quiet on the market. There is only today and tomorrow left before the end of the period and no one needs pounds," said one of the traders.
Five banks out of 11 contacted by Reuters had dealt overnight money at rates between one and four percent, compared with rates between seven and 10 percent on Thursday.
One bank had dealt one-week money at nine percent, versus a range of between nine and 11 percent in the last session.
The overnight CAIBOR rate fell to 10.6310 percent from 10.8929 percent on Thursday. The one-week CAIBOR rate slipped to 11.2500 from 11.3690 percent in the last session.
On the foreign exchange market, the pound last traded at a midrate of 6.20 in banks and 6.19 in exchange bureaux, around Thursday's closing weighted average of 6.21 pounds. Two market sources said the dollar would buy between 6.26 and 6.30 pounds on the black market, around recent levels.