The naira fell to 188.20 to the dollar on Friday, after it opened at 185.75, the same level it closed at the previous day.
Dealers said dollar liquidity in the market had dried up in the face of demand from importers buying foreign goods to sell in Nigeria, which imports around 80 percent of what it consumes.
Oil firms normally sell dollars to the interbank monthly to buy naira for their local operations, but dealers said this had not happened on Friday.
The central bank has intervened to help prop up the naira and also meet dollar demand but pressure on the local currency is still mounting in the wake of plunging global oil prices.
The bank was forced to devalued the naira two months ago to halt the slide in its foreign reserves. It devalued the naira by 8 percent and tightened trading rules to try to curb speculation against the currency.
But the naira has traded well outside its devalued band of 160-176 - and reserves are still falling.
Nigeria's foreign exchange reserves on Jan. 13 were down 3.2 percent month-on-month from December to $34.51 billion by Jan. 13 because of drawdowns to defend the naira, central bank data showed.