A spokesman for Iraq's military says the alleged suicide bombing by Melbourne teenager Jake Bilardi in Iraq yesterday achieved nothing.

If the propaganda of the Islamic State (IS) militia is to be believed, Melbourne teen Jake Bilardi blew himself up in an attack on the Iraqi army in Ramadi, west of Baghdad, but Iraqi military spokesman General Tahssin Ibrahim said the sacrifice came to very little.

He said the attack on Iraq's 8th Army Brigade at Ramadi had resulted in no fatalities among the security forces, only injuring several soldiers and damaging some cars, although his account cannot be independently verified.

The attack was part of a wave of car bombings, which have killed at least five people in Ramadi, west of Baghdad.

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General Ibrahim said western recruits to the Islamic State militia were being lured by false promises of glory and paradise, and said the attacks in Ramadi were launched because Islamic State was losing ground on the major battle front of Tikrit, north of Baghdad.

He urged Australians considering joining the fight to think again.

"My message is please take care about your family," General Ibrahim said.

"Think about your family, please, please think about that. Don't do anything and put yourself in the hell without any reason so this is my notation for young Australian people.

"Think about [your] education, maybe you can do something useful for [your] country, for the world."

According to a blog attributed to Bilardi, before the Melbourne teenager moved to Ramadi, he waited in vain to carry out a suicide operation near Baji, a valuable oil refinery just north of Tikrit.

Had he remained in place, he would have witnessed what is now the fiercest battle against his IS militia hosts.

The Sunni extremists have held the largely Sunni city since the middle of last year. But the Shiite-dominated army, backed by Shiite militias and Shiite advisers from Iran's military, are steadily gaining ground.

The battle has highlighted concern Iraq's sectarian divisions will be made worse as the campaign wears on.

Tikrit is just a small operation compared to what will be required to retake the much larger northern city of Mosul, and hanging over this whole campaign, is the involvement of the Iranian military.

Shiite politician Muien Al Kazzimy said: "Of course the role of the Islamic republic of Iran is important. It has saved Iraq. Their advisors attended the battle field, they've gave us their blood!"

But Sunni politician Thaffer Al A'anni vehemently disagreed.

"The presence of the Iranian revolutionary guards corp is clearly provocative, especially when it is completely against the desire and wish of the Iraqi politicians in these districts," he said.

Even after Tikrit falls, the Iraqi government will have a big job winning back the hearts and minds of the country's Sunni minority.