On Monday, the bank auctioned $100 million in forwards to be settled between one week and 30 days' time, as against 60-day contracts it had written previously, shortening the settlement period on forward contracts to inject liquidity.

The naira was quoted at 410 per dollar on the black market on Tuesday, weaker than the 405 it closed at the previous day. It closed flat on the official market at 306.10 naira.

The central bank, opposed to a free naira float, has been selling the US currency on the official currency market to try to narrow the spread with the black market rate after the black market rate hit a record high of 520 in February.