* Central bank head says $20 bln oil revenue unaccounted for
* State-oil company denies fraud allegations
* Effort to shed light on fuel-subsidy payments
By Joe Brock
ABUJA, Feb 13 (Reuters) - Nigerian lawmakers investigating a claim that the state oil company has failed to remit $20 billion in oil revenues ordered a forensic audit of fuel-subsidy payments on Thursday to find out where the money has gone.
Central Bank Governor Lamido Sanusi wrote a letter last September to President Goodluck Jonathan saying almost $50 billion in revenues from oil exports from January 2012 to July 2013 had not been remitted to the federation account, in a clear violation of the law.
He later lowered the estimate to $20 billion in his testimony to a Senate committee investigating the case. On Thursday, that committee grilled the finance minister, oil minister and Nigerian National Petroleum Corporation (NNPC), which denies Sanusi's charge that it runs fraudulent rackets.
The governor's suspicion of massive fraud at the heart of one of the world's most opaque state oil companies has put pressure on Jonathan a year ahead of elections, when he is already reeling from a failure to quell a northern Islamist insurgency.
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 currency fell to an all-time intraday low of 167 to the dollar on Thursday, driven by foreign portfolio outflows, until the bank intervened.
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.
NNPC says it buys kerosene at 150 naira a litre and sells it to suppliers at 50 naira per litre. But the retail rate is still 150 naira, which Sanusi said showed the subsidy was just "rent generated for the benefit of those in the kerosene business".
He also says a directive in 2009 by then President Umaru Yar'Adua, who died in May 2010, scrapped kerosene subsidies. Petroleum Minister and NNPC Chair Diezani Alison-Madueke told the committee they continued to subsidise kerosene despite the presidential order to prevent hardship for Nigerians.
"This illegality must end," Senator Ibrahim Gumba said at the hearing. NNPC had no legal right to ignore a presidential order or to collect a subsidy that was not allocated, he said.
The head of the committee, Senator Ahmed Makarfi, told the finance ministry to set up an independent audit of subsidy claims approved for NNPC by the petroleum regulator PPPRA, which came under scrutiny in 2012 over a separate multi-billion-dollar fuel subsidy fraud involving private companies.
Finance Minister Ngozi Okonjo-Iweala agreed to organise a forensic audit.
Amongst the things that need explaining are the fact subsidies were being paid out on 54 million litres of fuel per day, even though Nigeria only consumes 40 million litres per day - a discrepancy that lay behind a previous subsidy scam.
Sanusi also says that some of the $6 billion that NNPC's producing arm, NPDC, earned during the period should have been submitted to government accounts. Instead, it has been funnelled into private hands through special deals given to oil companies.
NNPC has been criticised in several investigations in recent years but consistently denies any wrongdoing.
"It is a lack of communication and misunderstanding which are causing these embarrassments," Alison-Madueke said. (Editing by Larry King)