Agents from Nigeria's intelligence and financial crimes agencies have detained the former presidential security adviser and several others over missing billions of dollars meant to buy weapons to fight Boko Haram.

PR Nigeria, which publishes government news, said the Department of State Security on Tuesday took former national security adviser Sambo Dasuki to its offices for questioning. Dasuki has said he is innocent.

The Economic and Financial Crimes Commission arrested former minister of state for finance Bashir Yuguda and other officials accused in the arms scandal, according to an official who insisted on anonymity because he is not authorized to brief reporters.

They are the first detentions since President Muhammadu Buhari on Nov. 18 ordered the arrests of former officials allegedly involved in fraudulent arms contracts worth $5.4 billion.