An Iraqi military spokesman showed the picture of a bearded man in a black T-shirt at a news conference on Tuesday. Maj. Gen. Qassim al-Moussawi claims it's Abu Omar al-Baghdadi but gave no other proof of identity.
Iraq's government announced al-Baghdadi's capture last week but the claim met with skepticism due to similar announcements that proved false.
The arrest of the head of the Islamic State of Iraq could mark a setback to insurgents trying to intensify attacks after a relative lull.
Al-Moussawi says al-Baghdadi was arrested April 23 and security forces are trying to glean information from him.