Femi Adesina, an adviser to President Muhammadu Buhari, says thousands of lives could have been saved if the money had been properly spent.
His statement yesterday accused Sambo Dasuki, a key adviser to former President Goodluck Jonathan, of awarding "phantom contracts" to buy 12 helicopters, four fighter jets, and munitions that were never supplied.
The State Security Service had said Dasuki was refusing to answer questions about the arms deal. Dasuki has been under house arrest for more than a week despite a court order allowing him to travel abroad for medical care.