The Department of Foreign Affairs is investigating reports that an Irishman died in a suicide attack near the Iraqi city of Mosul, a spokesman said today.

Yesterday, the so-called Islamic State's al-Jazeerah Province in northern Iraq said 'Abu Usama al-Irelandi' detonated an explosive-laden vehicle, killing and wounding dozens, the SITE Intelligence Group, a US company that monitors Islamist websites, reported.

Abu Usama is a pseudonym used by Irish IS sympathiser Terence Kelly. Pictures posted by IS sympathisers on Twitter showed a man resembling Kelly posing with a machine gun in front of an armoured car.

The Department of Foreign Affairs said it was looking into reports of an Irish citizen's death, but declined to comment on the person's identity.

"The department is aware of media reports concerning an Irish citizen in Iraq and is seeking to clarify the situation," a Foreign Affairs spokesman said.

Kelly was brought up Catholic in the Liberties area of Dublin and converted to Islam in his early 30s in Saudi Arabia, where he worked as a nurse for three years.

He converted to Islam in prison after he was arrested for illegally brewing alcohol. He also used the pseudonym Khalid Kelly.

Kelly repeatedly praised al Qaeda and Osama Bin Laden in interviews with the media and was arrested in 2011 for making threats against US President Barack Obama ahead of his visit to Ireland.

He travelled to Pakistan and later told interviewers that he had trained with militants there.

Iraqi troops advanced towards Mosul today, battling for the last town left between them and the IS stronghold to the north, which was already under assault from special forces inside its eastern districts.

Recapturing Mosul would effectively crush the Iraqi half of a self-proclaimed caliphate declared by IS leader Abu Bakr al-Baghdadi from the pulpit of a Mosul mosque two years ago. His Islamist group also controls large parts of east Syria.