Startling allegations of corruption have been made in Nigeria which, if proved true, will constitute a shocking indictment of the former president Goodluck Jonathan. Five top officials are accused of stealing immense sums that had been earmarked to provide Nigeria's poorly-equipped army grappling with Boko Haram fanatics in the north of the country. No less than $2.1 billion is supposed to have been spirited away in a theft which is typical of the long-standing plunder that as taken place in Africa's most populous and - with its substantial hydrocarbon resources - potentially its richest nation. The accused include Sambo Dasuki, Jonathan's national security adviser. All deny the allegations, saying that the money was in fact spent on weaponry, helicopters and mercenaries, who briefly stopped the Boko Haram terrorists. Yet the Nigerian investigators say they can find no auditable paper trail that proves this defense. Dasuki and his former colleagues are the first officials to face trial under the anti-corruption drive promised by the new president, former general Muhammadu Buhari. Jonathan made similar promises to clean up widespread venality among politicians, the bureaucracy and top officials in state companies. Yet all the indications are that the looting of state coffers actually increased under a man who arguably proved to be Nigeria's least successful president. Buhari is in his second term of office. He seized power in a coup in 1983 which overthrew the democratically-elected government of President Shehu Shagari. That coup was prompted by massive state corruption. And during his two years in power, the no-nonsense general did begin to initiate a clean-up, which, however, included widespread and unpopular job losses. This time Buhari has come to office with a popular mandate to set about the sink of corruption that his country has become. He has made it clear that wrongdoers will be punished. He wants to restore economic stability and ensure that government revenues are spent properly, not spirited off to Swiss bank accounts. His principle text is that the rot at the top has corroded society as a whole. It is clear that many ordinary Nigerians have become cynical. They have seen officials helping themselves to state funds and refusing to act without bribes. They have heard politicians promise so many times to clean up payola that they no longer believe them. Many take the view that if everyone else is on the take, then for the sake of their families, it would be stupid of them not to join in as well. Buhari, therefore, very probably represents a rare opportunity, possibly even the last chance, for Nigeria to set its deeply tainted house in order. The trials are a key opportunity to prove that he means business. Cracking down of fraudulent accounts, tracking down billions of stolen funds and restoring order to the country's public sector are vast challenges. Buhari is attacking a disease that has infected every area of public life and indeed the wider business community. And he has a further task, which is to overcome the incompetence and inertia that characterize the state sector which has seen such spectacular waste in massive projects, such as brand new power stations that break down within months because they have not been maintained and managed properly. And all the while, he must also confront the savage Boko Haram rebellion in the north with a currently demoralized, badly-trained and poorly