President Buhai has ordered 20 former military chiefs and officers to be investigated over alleged arms procurement fraud.
Among them are the chiefs of defence and air staff under the last administration.
President Muhammadu Buhari’s office said it was “on the recommendation of” a committee set up to examine procurement from 2007 to 2015.
The activities of 20 companies will also be investigated.
One of the names on the list is of a former security adviser to the government. Sambo Dasuki was charged in December over an alleged $68m fraud. He was accused of awarding phantom contracts to buy helicopters, fighter jets and ammunition.
He denied the allegations and said they were politically motivated.
A previous investigation found that phantom contracts worth $2bn had been awarded.
During the fight against Islamist militant group Boko Haram, many soldiers reported that they did not have enough equipment to take on the insurgents.
Others on the list include Alex Sabundu Badeh, a former chief of defence staff, and the former chief of air staff Adesola Nunayon Amosu. Both served under former President Goodluck Jonathan.
President Buhari was largely elected on a promise to tackle corruption.
The Economic and Financial Crimes Commission (EFCC) is spearheading the anti-corruption campaign.