Lagos - Nigerian President Goodluck Jonathan has suspended Central Bank Governor Lamido Sanusi, an increasingly outspoken critic of the government's record on tackling rampant corruption, the presidential spokesman said on Thursday.
Deputy Governor Sarah Alade was appointed acting governor.
Sanusi, who was due to end his term in June, had been presenting evidence to Parliament which he said showed the state oil company had failed to remit around $20-billion that it owed to federal government coffers.
The naira fell more than one percent to 165.80 to the dollar on the news.
"Mallam Sanusi Lamido Sanusi's tenure has been characterised by various acts of financial recklessness... inconsistent with the administration's vision of a Central Bank propelled by the core values of focused economic management," a statement from the spokesman said.
The governor's suspicion of massive fraud at the heart of one of the world's most opaque national oil companies has put pressure on Jonathan a year ahead of elections, when he is already reeling from a failure to quell an increasingly violent Islamist insurgency in the north.
The state oil firm - Nigeria National Petroleum Corporation (NNPC) - has repeatedly denied Sanusi's allegations.
It has also spooked debt investors worried about government squandering of oil revenues during election cycles. Sanusi says graft is slashing forex reserves needed to support the naira.
The biggest gap in accounting is for $8.5-billion the NNPC says it retained from revenues during the 19-month period to cover subsidies it was owed on importing gasoline and kerosene.
Sanusi also says that some of the $6-billion that the NNPC's producing arm, NPDC, earned during the period should have been submitted to government accounts. Instead, he says, it has been funnelled into private hands through special deals given to oil companies.