Nigeria's army says 12 senior officers are being investigated for corruption.

It's unclear if the investigation is linked to a $2.1 billion scandal in which money meant to buy weapons to fight Boko Haram extremists was diverted, including to the former president's re-election campaign.

Col. Sani Kukasheka Usman says the army has handed the Economic and Financial Crimes Commission the cases of three major generals, three brigadier generals, four colonels, a lieutenant-colonel and a retired major general for investigation.

The commission already is questioning a slew of military officials.

Officials blame corruption for the deaths of thousands, saying the graft left soldiers unable to protect civilians from Boko Haram Islamic extremists.