(Transcript from SBS World News Radio)
Prime Minister Tony Abbott says he's worried about the influence of what he calls "an ISIL death cult" on a Sydney shooting.
Rasoul Al Mousawi was shot in the face outside a Shia Muslim prayer hall in the early hours of Monday morning.
However, sources within the community say a factional dispute was the cause of the conflict.
As Darren Mara reports, the violent incident has spurred many Muslims to attend processions for the Day of Ashura in solidarity against the attack.
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Thousands of Shia Muslim men, women and children sing in Sydney's Hyde Park for the annual Ashura march to the Royal Botanic Gardens.
The peaceful procession marks the anniversary of the murder of Imam Hussain, who was killed alongside his family in Iraq 1,300 years ago.
Ashura this year comes at a sensitive time for the Muslim community.
And tensions have been exacerbated by the shooting of a Shia Muslim leader outside a mosque in Sydney's southwest.
Rasoul Al Mousawi has undergone surgery and is now recovering in hospital.
Muslim leaders speaking at the Ashura rally - which was mirrored by a similar event in Melbourne - have vowed not to be intimidated by the violent incident.
A banner leading the Sydney march read: "Terrorists have risen again, who will be victorious over them?"
Stayed Moustafa Al-Qazwini was among the Ashura marchers.
He says he turned out as a show of defiance against those who carried out the mosque attack.
"Incidents of terrorism against the peaceful people makes us more resolute in showing ourself and fighting terrorism. It would not make us shy away and run away. I think the incident of yesterday, in one of the mosques here, made many people to come and participate in this march, and I am one of them. I had no intention of coming but when I saw the clip on television yesterday, I said, I have to stand against this."
Witnesses say a group of men drove past the Sydney mosque before the shooting, calling out slogans used by the self-proclaimed Islamic State - a Sunni extremist group trying to establish an Islamic caliphate in the Middle East.
However, some sources within the community dispute involvement of any IS supporters and say the shooting was over an internal dispute.
Muslim community leaders acknowledge there is an ongoing dispute between two Shia groups.
But they say it is being resolved and would not have escalated to this level.
Prime Minister Tony Abbott says he's concerned the shooting highlights the growing impact of IS in Australia.
"Well obviously we saw the attack no two policement in Victoria a month or so back. It seems there is an ISIL death cult influence on this shooting in Sydney in the last 24 hours or so. The important thing is for all of us to absolutely reject this death cult."
The police say they do not believe the incident is linked to IS.
But Sydney Muslim leader Jamal Daoud says there is concern in the community of extremist elements.
"The police are in denial that this is an attack related to extremism in society. We started to hear from some of the young people that they should take the law into their own hand and should retaliate, tit for tat attacks which would be very dangerous for society."
Whatever the cause of the shooting, there is evidence of the rise of IS in Australia.
An Australian fighting with the militants in Syria claims another Australian man has been killed.
Abu Noor al-Kurdi is believed to have died alongside the nation's most senior IS figure, Mohammad Ali Baryale.
He died during coalition airstrikes on the Syrian border town of Kobani.
The government is trying to verify the claims.