Nigeria’s sacked national security adviser, Sambo Dasuki, has been charged in court with illegally possessing weapons, an official statement has said.
Firearms were seized during a raid on his properties last month, it added.
Mr Dasuki denied any wrongdoing at the time and said the weapons belonged to his security guards.
He is the first senior official of the former government to be charged under President Muhammadu Buhari’s rule.
Mr Buhari took office in May after defeating former President Goodluck Jonathan in elections.
In a separate statement, his office said he had ordered an investigation into military equipment bought since 2007.
The investigation was part of an effort to curb corruption and ensure that the military was properly equipped, it added.
Mr Buhari replaced Mr Dasuki and other security chiefs last month in a renewed effort to end a six-year insurgency by militant Islamist group Boko Haram.
The Department of State Security said the decision to charge Mr Dasuki was in line with its commitment to upholding democratic values.
No-one was above the law, no matter how highly placed they were in society, it added in a statement.
Analysis: Mansur Liman, Editor, BBC Hausa Service
Mr Dasuki played a prominent role in the fight against terrorism during Goodluck Jonathan’s rule.
Many accused him of not only advising him on security issues, but also of taking over the responsibility of the Ministry of Defence.
It was clear that the defence minister at the time, Aliyu Gusau, was sidelined during the last few months of the Jonathan government.
Mr Dasuki was at the centre of a row over Nigeria’s unorthodox arms procurement in 2014, when South Africa seized suitcases packed with millions of dollars of cash at an airport in Johannesburg.
The Nigerian government said the money was intended to purchase weapons for the fight against Boko Haram, and denied allegations of corruption.
Mr Dasuki argued for the postponement of Nigeria’s presidential elections earlier this year, citing the security situation.