The mark of African political leadership has too often been characterised by the reneging on pledges of clean government and indulging in corruption. There are, of course, exceptions to this rule. Yet, regrettably, the political classes of my continent have often behaved like those who suffer from an addiction – blaming others for those consequences made by their own hands. But as with all addiction sufferers, eventually it is no longer possible to elude responsibility, and they are inexorably led to the day of reckoning.

This made the first African Anti-Corruption Day this week, for all 55 countries of the African Union, an important step in recognising both the realities and responsibilities for corruption. It is symbolic, of course, as is my appointment as the first AU champion on anti-corruption – but it is a call to action.

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The AU’s recent Mbeki report calculated that as much as $50bn (£38bn) is misappropriated from my continent each year – more than three times the US overseas development assistance to Africa. The recovery of this amount would be transformational, as billions of Africans suffer when hospitals are without basic services, schools without chairs, people without water and young people without jobs. That is the consequence of this corruption, when vast sums are stolen from the wealthy: for it is impossible to steal such amounts from paupers. It is theft that makes the citizens of Africa poor when they should be rich.

There will be those who doubt the capacity of Africa’s peoples to take on corruption with any great success. There has been much hope followed by much failure before. But doubters need look to the fundamental change these very same citizens bring across my continent every month through the ballot boxes of Africa’s many fast-maturing, multiparty democracies: this is change made possible for millions by access to information and organisation that they have seized and harnessed through improved communications and social media.

Ejection and election is today made rapid by this great power and, understandably, brings great expectations of those assuming office. It is a power to hold them accountable for success or failure – a power few African politicians, or leaders of the international community, truly thought would ever hold.

What my election as Nigerian president – much due to a campaign made possible by mass communication – has taught me is that democracy’s strength comes from this accountability, and the demand that the rights of all are equally upheld. This includes the right of those accused of crimes of corruption to a fair trial before an impartial court of law, and to be believed innocent until proven otherwise.

When once I was army head of state, special military tribunals – not civilian courts – heard corruption cases. Trials could be hastened, as lawyers to defend the accused often preferred not to be found. Arrests were quick, as were verdicts. This was possible because I was not accountable, something my younger self might well have viewed a distraction. But the absence of that accountability has allowed others to steal and be corrupt with impunity.

We are fast transitioning to the time when political accountability in Africa becomes no longer the new but simply the expected – but we are not there yet. That is why our citizens’ campaign will force those who steal to be held accountable too. For just as a thief does not steal successfully without a place to hide their stolen goods – so an addiction needs a supplier. That is why action against corruption requires its recognition and treatment both for its perpetrators and its enablers.

• Muhammadu Buhari is president of the Federal Republic of Nigeria and the African Union’s champion on anti-corruption