The Iraqi government presented the first image of the alleged leader of an Al Qaeda front group Tuesday in a bid to prove the right suspect was in custody despite skepticism that he even exists.

Prime Minister Nouri al-Maliki called Abu Omar al-Baghdadi "the head of evil" and accused him of trying to incite a sectarian civil war and working with other insurgents who remained loyal to Saddam Hussein.

"This criminal had close relations with the former regime and maintained a sinister alliance with Saddam's followers," he said in a statement released by his office.

Authorities described al-Baghdadi's capture, which was announced last week, as a major setback for Sunni insurgents trying to intensify attacks after a relative lull.

But the capture or death of other high-ranking insurgent figures in the past — including former Al Qaeda in Iraq leader Abu Musab al-Zarqawi in 2006 — has done little to slow the bombings.

Pentagon spokesman Bryan Whitman said he could not confirm al-Baghdadi's capture and described as "fairly accurate" a statement that every day that goes by without a confirmation increases the suspicion that it's not him.

A prominent writer identified as Muhub Ruyat al-Rahman, whose comments are widely read on Islamic Web sites, meanwhile, signaled that insurgent groups also were not certain the man captured was al-Baghdadi.

He warned his comrades the claim could be a propaganda ploy and said even if it did prove true, the death or arrest of leaders would not stop the march of jihad, or holy war.

The identity of al-Baghdadi — shown in the photo unveiled at a news conference with a close-cropped beard and black T-shirt — has frequently been questioned.

The U.S. military has even said al-Baghdadi could be a fictitious character used to give an Iraqi face to an organization dominated by foreign Al Qaeda fighters. Even if he does exist, it was unclear what his role is in the terror group — whether he really runs it or whether he's a figurehead.

Iraqi officials also have reported al-Baghdadi's arrest or killing before, only to later say they were wrong.

In 2007, Iraq's government reported that al-Baghdadi had been killed and released photos of what it said was his body. Later, security officials said they had arrested al-Baghdadi. In both cases, the U.S. military said at the time it could not be confirmed. The reports turned out to be untrue.

But Iraqi military spokesman Maj. Gen. Qassim al-Moussawi said the government was certain the man arrested Thursday was al-Baghdadi. He displayed the picture but offered no other proof, saying the investigation was ongoing and that security forces were still trying to glean information from the detainee.

A senior Iraqi security official said authorities did not want to release too much information because it could tip off members of his insurgent network.

Information from al-Baghdadi already had led Iraqi authorities to arrest four people, including a woman, and seize three explosive belts in Diyala province, north of Baghdad, the official said on condition of anonymity because he wasn't authorized to release the information.

He said the group had planned attacks to mark the birthday of Saddam, who was hanged in 2006. Saddam, who is buried in the Tigris River hamlet of Ouja, would have turned 72 on Tuesday.

Authorities hailed the purported arrest as a major victory for Iraqi forces reeling from accusations that they are not prepared to take over their own security in the wake of a series of high-profile attacks.

The deadliest bombings in more than a year occurred last week after al-Baghdadi was purportedly caught, with more than 150 people killed over a period of two days.