The African Development Bank says it has commissioned an independent inquiry into allegations of corruption against its head, Akinwumi Adesina.

The former Nigerian agriculture minister is seeking re-election in August.

But the United States has led calls for him to be investigated on suspicion of embezzlement, preferential treatment for fellow Nigerians in senior appointments, and the promotion of people suspected or convicted of fraud and corruption.

Mr Adesina denies any wrongdoing and was initially cleared of the allegations by an internal investigation.

The institution – one of the world’s five major multilateral development banks – is the only African lender afforded the highest credit rating.

In April, whistleblowers submitted a 15-page report to the bank’s governors detailing alleged embezzlement, preferential treatment for fellow Nigerians in senior appointments, and the promotion of people suspected or convicted of fraud and corruption.

Adesina — who was recently exonerated by an internal inquiry — is the first Nigerian to be in charge of the 56-year-old AfDB, one of the world’s five major multilateral development banks.

Nigeria, whose stake makes it the bank’s biggest shareholder, has made little secret of its support for Adesina.

On Tuesday, Nigerian President, Maj. Gen. Muhammadu Buhari [retd], told Adesina that the country “will stand solidly behind” him in his bid to remain at the helm of the bank.

The bank chief repeated to Buhari his insistence the allegations against him were trumped up and that the US call for a new probe was against the bank’s rules.

In October 2019, the AfDB raised $115 billion (105 billion euros) in fresh capital, an operation deemed a personal success for Adesina.

It is the only African institution which has a Triple-A rating by credit rating agencies.