ABUJA (Reuters) - Nigeria has arrested the chairman of a local oil firm, a security official said on Tuesday, as part of a widening graft investigation in Africa's biggest petroleum producer that has also netted former oil minister Diezani Alison-Madueke.
Days after British police detained Alison-Madueke, one of Africa's most powerful women, the official said their counterparts in Nigeria's Economic and Financial Crimes Commission (EFCC) had arrested Atlantic Energy chairman Olajide Omokore on corruption and money laundering charges.
The arrests, which follow pledges by President Muhammadu Buhari - a former military dictator - to "clean up" Africa's biggest economy, have sent shockwaves through Nigeria's globe-trotting corporate and political elite.
"A lot of people have been shocked," one oil executive in Nigeria told Reuters. "The net is widening and it's not clear how deep the rabbit hole goes. There will be a few people looking over their shoulders."
The EFCC official said Omokore, listed by Forbes magazine in 2012 as one of "Ten Nigerian multi-millionaires you have never heard of", remained in custody.
"He is being interrogated," the official, who did not want to be identified, told Reuters. He gave no further details.
Omokore's lawyer and a spokesman for his company could not be reached for comment.
Alison-Madueke, whose house in Abuja was raided by Nigerian police on Friday night, was accused by former central bank governor Lamido Sanusi of presiding over a state oil sector that leaked tens of billions of dollars during her five-year tenure.
Sanusi was sacked by then-President Goodluck Jonathan after raising concerns that $20 billion in oil revenues had not been remitted to government coffers by the state oil firm, NNPC, between January 2012 and July 2013.
Sanusi also criticised Alison-Madueke for giving Atlantic - then an unknown start-up - a major contract with the NNPC shortly after becoming oil minister in 2010. She left office in May after Buhari's election victory over Jonathan two months earlier.
Alison-Madueke has denied any wrongdoing. Attempts to reach her in London have been unsuccessful.
