The Naira firmed 1.1 percent on the black market on Wednesday to a six month-high of 430 per dollar, traders said.
It was quoted at 307.50 on the interbank market.
The central bank has been intervening on the official market to try to narrow the currency spread. The black market rate was 520 a month ago.
“The regular intervention by the central bank has increased liquidity in the official market. The new policy has also eliminated spurious demand for the dollar,” Aminu Gwadabe, the head of Nigeria’s exchange bureaux told Reuters.