LAGOS, March 7 (Reuters) - Nigerian interbank lending rates eased marginally to an average of 10.66 percent on Friday, from 10.75 percent last week as the central bank credited lenders with funds in excess of the amount it had taken to enforce its cash reserve ratio (CRR).
Dealers said the central bank had withdrawn about 107 billion naira ($651.1 million) above its CRR limit when it debited lenders last month and has had to refund the excess, boosting liquidity in the system.
On Friday, the cash balance that lenders hold at the central bank opened at 429.61 billion naira in surplus, compared with 446 billion naira last week and sufficient to support transactions in the market.
Traders said additional inflows of 212 billion naira in open-market operations' (OMO) matured bills was injected to the banking system on Thursday.
The secured open buy back (OBB) rate was flat at 10.5 percent, 1.5 percentage points below the central bank's benchmark rate of 12 percent.
The overnight placement rate was also unchanged, at 10.75 percent, while call money closed slightly lower at 10.75 percent compared with 11 percent last week.
"We expect the market to remain liquid by next week and rates flat with the planned injection of about 320 billion naira in matured OMO and bonds, but the cost of borrowing could inch up a little if the central bank embarks on aggressive liquidity mopping up," one dealer said. ($1 = 164.35 naira) (Reporting by Oludare Mayowa; Editing Chijioke Ohuocha and Susan Fenton)