Abuja - Attorney General of the Federation has filed charges against a rep, Farouk Lawan and a House committee secretary, Boniface Emenalo.
Farouk Lawan blew the lid on a $6.8 billion scam in a state fuel subsidy, exposing a web of fraudulent transactions that enabled corrupt officials and fuel marketers to grow rich, often without delivering a drop of fuel.
He pleaded not guilty in court on Friday to four counts of bribery brought against him by the federal government and his supporters say he is being targeted by those implicated in his investigation.
Africa's largest crude exporter has to import 80 percent of its fuel needs because its refineries are in disrepair. The government pays a subsidy on the fuel, which breeds corruption and is the single biggest drain of the federal budget.
Lawan's arrest risks discrediting his findings, although two subsequent independent probes have come to similar conclusions.
He is accused of taking $500,000 - part of an agreed $3 million bribe - from Femi Otedola, one of Nigeria's richest men, to keep his oil firm Zenon Petroleum out of his report.
"You Farouk Lawan ... in the course of your official duty corruptly asked for the sum of $3 million for yourself from Femi Otedola ... to afterwards show favor to Femi Otedola," charges read in the Abuja High Court said.
The judge ordered that Lawan be remanded in police custody until a bail hearing on February 8.
Another member of Lawan's parliamentary fuel subsidy committee, Emenalo Boniface, is charged on three counts for also demanding the bribe from Otedola, who will not face prosecution because he told the authorities about the deal.
Lawan's supporters say this is evidence he was a set up by President Goodluck Jonathan's administration, in collusion with Otedola, because they were embarrassed by his findings.
Lawan's lawyer said last year that the case was a conspiracy brought by fraudulent oil marketers and powerful government officials who wanted his report discredited. He said Lawan accepted the bribe only to expose Otedola, saying he disclosed the payment to parliament and left the cash there.
If Lawan is found guilty it could end any attempt to seek justice in the subsidy scandal, an outcome likely to please Nigeria's powerful oil marketers and some corrupt government officials, but enrage the public.
The report fingered several fuel companies, including a local unit of ExxonMobil, as being involved and called for the board of the state oil firm, including its head Oil Minister Diezani Alison-Madueke, to resign.
Lawan's report was scathing about some of Nigeria's most powerful people - few would dare take on the oil minister - and was an embarrassment to Jonathan, whose office pledged to prosecute those implicated but urged patience.