Nigeria's President Goodluck Jonathan has suspended the central bank governor who announced that billions of petrodollars were missing from government coffers.
Lamido Sanusi, the internationally-respected governor, could not immediately be reached for comment after the president's announcement on Thursday.
But a statement from the president's aide said: "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."
Last year, Sanusi reported that $50bn worth of oil sold by the state-owned Nigeria National Petroleum Corporation (NNPC) had not been paid to the government.
The Senate Committee on Finance last week ordered an independent forensic audit into the missing money, which it said amounted to about $20bn.
Missing receipts were said to account for the rest.
The naira fell more than one percent to 165.80 to the dollar on the news, the Reuters news agency reported.
Jonathan appointed deputy governor Sarah Alade to replace Sanusi, who had been expected to step down this year.
Pressure on president
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 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 $8.5bn 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 $6bn 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.
Sanusi was named as the Central Bank Governor of 2010 for both the African continent and the entire world, by the prestigious Banker magazine.
The editor of the magazine said then that few candidate names generate an overall consensus on judging panels but that Sanusi had been chosen unanimously as the best global central bank governor of the year.
Appointed in the midst of a debt crisis in 2009, Sanusi is also credited with reforming Nigeria’s banking sector by taking controversial decisions, including firing the chief executives of eight leading banks over huge non-performing loans.