In a circular seen by Reuters on Thursday, the central bank asked all bureau de change operators to submit accounts showing their dollar usage at the start of each week before they can access future sales, a move traders say was aimed at curbing speculation.
The naira had fallen sharply on Wednesday, a day after the central bank unexpectedly cut interest rates to stimulate lending in Africa's biggest economy, traders said.
The currency was quoted at the pegged rate of 197 naira on the official interbank market on Thursday.