A British preacher considered so extreme in his home country that he has been kicked out of mosques and spurned by the Islamic community has turned his gaze to Australia and is quickly building a support base in Sydney and Melbourne.
Abu Haleema, who had his passport cancelled in Britain and was arrested on terrorism offences last year, has produced YouTube videos in recent weeks attacking moderate Sydney sheikhs Shady Alsuleiman and Wesam Charkawi. 
He also attacked Liverpool imam Sheikh Abu Adnan for allowing Bankstown policeman, Danny Miqati, to give a talk in the mosque about domestic violence.
However, Australian authorities are powerless to stop Haleema from spreading his hardline sermons on YouTube and Facebook, where he is gathering a following among young Australians including some of those on the periphery of a group charged over the murder of police accountant Curtis Cheng.
Counter-terrorism police told Fairfax Media they were aware of Haleema's influence but could do little other than monitor his online interactions.
"This is the problem, a lot of the influence is coming from overseas via the internet," said one officer.
On Tuesday, Britain's Channel 4 aired a documentary, The Jihadis Next Door, in which a filmmaker spent two years with Haleema and his small group of extremist preachers.
It shows them being turned away from mosques and preaching on the streets, where British Muslims yell abuse at them for brainwashing teenagers and supporting Islamic State.
Haleema doesn't speak Arabic and has no formal qualifications. His videos resemble rap videos, filmed in front of graffiti walls or underground train tunnels and shouted in a fast, repetitive style.
It's not known why Haleema has turned his focus to Australia, however he is receiving a warm reception.
"He's definitely playing to the audience here," said one Sydney Muslim leader, who asked to remain anonymous. "People follow him because he's so staunch and he's attacking the leaders who are trying to do the right thing."
Melbourne-born Islamic State recruiter Neil Prakash previously hinted on social media that he was close with Haleema.
The preacher was also instrumental in radicalising the 14-year-old British boy who contacted Melbourne teenager Sevdet Besim and allegedly urged him to launch a terrorist attack on Anzac Day.
He had about 7000 Facebook followers until his page was shut down in mid-  December. His fans included several men targeted in Operation Appleby raids in Sydney.
On his newly-created fan page, a Gold Coast man said, "love your shirk shady video akhi its good to know you stand behind us".
In the video, Haleema attacked Sheikh Shady for giving Australian Muslims a fatwa, or religious ruling, allowing them to join the police, army and navy. He called the sheikh a "shirk", or idolater, for supporting democracy and non-religious law.
"It seems they're all in Sydney. Sydney needs to be re-named the land of the heretic scholars," he said. "Even the other day on Instagram, I seen someone saying they're joining the army coz Shady gave them a fatwa."
He berated the sheikh, who is widely-respected among the youth, for counselling a schoolboy who refused to stand for the "Anzac anthem" at school and for supposedly teaching the theory of evolution to students.
Sheikh Wesam, another youth worker respected for his grassroots deradicalisation efforts, is targeted for condemning the Paris attacks and for hugging a woman.
Edith Cowan University professor Anne Azza Aly, founder of People Against Violent Extremism, said the spread of such "online theological superstars" could only be fought by a young person's friends and family offering counter-narratives.
"What we can do is actually very little to be honest," she said. "I could come up with a video that challenged everything Abu Haleema says. The government could fund a counter-propaganda campaign. But it will never be as effective as when one friend says, "are you mad dude, why are you liking this guy?" That challenge has to happen in a very organic way."
The Grand Mufti has previously lamented the influence of "Sheikh Google and Sheikh YouTube," blaming it for the radicalisation of Farhad Jabar, the teen who killed Mr Cheng.
A spokesman for the federal Attorney General's Department said the government has invested $21.7 million to challenge terrorist propaganda and has partnered with social media companies and communications agencies to take down extremist material and build "digital resilience".
NSW Police said they routinely monitor social media. A spokesman said the key to silencing online hate preachers "will always be awareness and the reporting to authorities [of extremist material]".
Haleema has been contacted for comment.