By Patrick Smith Editor, Africa Confidential

The humiliation of Nigeria's ex-President Olusegun Obasanjo is forging ahead, less than a year after he left office.

Many Nigerians expected Mr Obasanjo to rule from behind the scenes

In the past few months, parliamentary committees have exposed allegations of government corruption during his eight-year tenure that sit uneasily with his image as a reformer.

Nigeria's press runs lurid tales of family scandals.

Investigators have charged his daughter, Iyabo Obasanjo-Bello, with complicity in a scam to defraud the health ministry.

A few months before the April 2007 elections, Mr Obasanjo anointed as his successor Umaru Musa Yar'Adua, a relatively little-known state governor from a great family in the Muslim north.

Many Nigerians expected the outgoing president to carry on ruling from behind the scenes, but Mr Obasanjo's influence has waned and his confidants say that the northern power brokers around Mr Yar'Adua are pursuing a vendetta that will cost him, at the very least, his reputation.

Some of them want him arrested.

Regional divide

Mr Obasanjo is from the south-west. His confidants argue that the powerful northerners, embittered by the liberal economic reforms and privatisations of his tenure, are taking revenge now that one of their own is back in the presidency.

OBASANJO 'WITCH-HUNT' May 2007: President Obasanjo stands down July 2007: Nigerian tycoon pulls out of purchase of oil refineries Feb 2008: Privatisation of former phone monopoly Nitel cancelled March 2008: Obasanjo ally loses vote to lead ruling party Obasanjo's government accused of funnelling $50m to fake companies Daughter Iyabo Obasanjo-Bello accused of receiving $85,000 from health ministry April 2008: Son-in-law Kenny Martins questioned over $42m missing from Police Equipment Fund Obasanjo ally Mallam Nasir el-Rufai accused of giving land to his and Obasanjo's relatives National Assembly launch probe into oil and gas under President Obasanjo Obasanjo family 'witch-hunt' Ex-leader in adultery case

The Obasanjo camp says that this is an attempt to victimise the family.

But one aide to Mr Yar'Adua maintains that Mr Obasanjo's final three years were the most corrupt since Nigeria's independence in 1960.

Both sides tend to agree that Mr Yar'Adua is not personally orchestrating the investigations into his predecessor.

The president's refusal to interfere in various parliamentary and ministerial inquiries is in line with his hands-off style, contrasting with that of Mr Obasanjo, who had a reputation for involving himself in the details of government business.

Since Mr Obasanjo played a key role in so many decisions, legislators want to find out how far he was himself involved in the dubious dealings they are unearthing.

The most sensational revelations stem from an inquiry into the power sector, begun by a panel in the House of Representatives after Mr Yar'Adua said in January that more than $10bn had been spent on electricity under the previous government, with little to show for it.

Score settling

Televised hearings revealing allegations of huge sums given to contractors for little or no work have rankled amid the chronic power crisis.

Nigeria's power supply remains patchy despite a $10bn investment

Some of the investigators' targets insist that the Abuja witch-hunt is inspired by a host of disgruntled elements with personal scores to settle.

The Senate, for example, is looking into some controversial land sales in the Federal Capital Territory (FCT) during the tenure of Mallam Nasir el-Rufai, one of Mr Obasanjo's favourite ministers.

Mr Rufai is alleged to have parcelled out land to members of his own family and the former president's.

He denies any impropriety; supporters note that the chairman of the investigation had his Abuja property bulldozed after building what the FCT said was an illegal structure.

The Senate has looked into the use of a special aviation fund by Femi Fani-Kayode, the former aviation minister, another Obasanjo ally.

Mr Obasanjo's name surfaced again when the government cancelled the sale of the Ajaokuta Steel Mill, for long a notorious white elephant, to Global Infrastructure Holdings Ltd, controlled by the world's leading steelmaker, Pramod Mittal.

A panel has concluded that the deal was skewed in favour of the company and Mr Yar'Adua has called for the prosecution of its "promoters".

Governors' glee

Mrs Obasanjo-Bello, the ex-president's eldest daughter, hit the headlines when the Economic and Financial Crimes Commission (EFCC), created by her father in 2003, charged her with involvement in a scam to defraud the health ministry.

Mr Yar'Adua dismissed Health Minister Adenike Grange and junior Health Minister Gabriel Aduku, accused by the EFCC of involvement in a plan to embezzle unspent ministry funds, following a directive that ministries should return unspent funds at the end of the year.

Iyabo Obasanjo-Bello says there is a witch-hunt against her family

The accusation was that Iyabo Obasanjo-Bello, as chair of the Senate Health Committee, received 10m naira ($85,000), which she claimed was for an official committee retreat in Ghana. EFCC agents have raided her home.

One interest group that cheers on every blow against Mr Obasanjo consists of those former state governors who were charged with corruption last year.

They lost their immunity from prosecution after stepping down at last April's elections and eight of them face graft charges.

They hope that evidence of abuse in the federal government under Mr Obasanjo will weaken the moral authority of the EFCC, a federal body, in prosecuting alleged offences at state level.

The inquiries also divert attention from the incumbents' failings.

Mr Yar'Adua earned the name of "Mr Go-Slow" after he took office last May, but has had some important victories in recent months.

He won an appeal to the presidential election tribunal in February.

In March, his supporters blocked attempts by Mr Obasanjo to foist his preferred candidate, Sam Egwu, into the chairmanship of the ruling People's Democratic Party.

There may be nasty surprises to come.

Some lawmakers are calling for an inquiry into the oil sector, in particular the running of the state-owned Nigerian National Petroleum Corporation, widely perceived as the home of some of Nigeria's most explosive scandals - and the source of gigantic sums of money.

A full version of this article appears in Africa Confidential, a fortnightly bulletin on African affairs