Abuja - Nigeria's former oil minister Diezani Alison-Madueke was arrested in London on Friday, a source from Nigeria's presidency circle and another with links to her family said.
She was minister under former president Goodluck Jonathan until May 2015.
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A police spokesman in London said he had no record of such an arrest. The National Crime Agency did not immediately respond to a request for comment.
A statement for the British High Commission in Abuja said that five people between the ages of 21 and 60 had been arrested on suspicion of bribery and corruption offences on Friday morning.
"The crimes are being investigated by the National Crime Agency," it said, without naming anyone.
Former central bank governor Lamido Sanusi was sacked while Alison-Madueke was in office after he raised the alarm over tens of billions of dollars of oil revenues that had been unaccounted for at state oil company NNPC between January 2012 and July 2013.
Reuters was unable to reach Alison-Madueke's personal assistant or a lawyer representing her, but she has previously denied to Reuters any wrongdoing.
Many Nigerians had been expecting her arrest after President Muhammadu Buhari officially replaced Jonathan at the end of May.
Buhari, a former general, won the elections at the end of March after promising to crack down on corruption, which is endemic in Africa's biggest economy.