The campaign group Transparency International says corruption in the Nigerian military is weakening the country’s efforts to fight Boko Haram insurgents.
It accuses officials of creating fake defence contracts and stealing money meant to provide vital equipment. It says this has left the army under-resourced and insufficiently trained.
A Nigerian defence spokesman Major General John Enenche, said the allegations did not apply to the current crop of military officers.
He said much had been done to improve training and boost the morale of troops.
Meanwhile, a schoolgirl who was abducted by Nigeria’s militant Islamists in 2014 has escaped from captivity, a presidential aide has told the BBC.
The girl was found by government troops while she was escaping, Femi Adesina said, without giving details.
She was among 276 girls seized by Boko Haram from north-eastern Chibok town in 2014, sparking global outrage.
A total of 103 of the girls have been released so far, including 82 earlier this month in a prisoner swap.
The 82 girls, who met Nigerian President Muhammadu Buhari on 7 May, are expected to be reunited with their families later this week.
They were escorted to a reception in the capital Abuja by armed soldiers, after a check-up at a medical centre.