A former Melbourne man linked to the alleged Anzac Day terror plot has appeared in an Islamic State (IS) propaganda video discussing his conversion to Islam and calling on his followers to attack Australia.

Neil Prakash, who goes by the name Abu Khaled al-Cambodi, is IS's most senior Australian recruiter and used the 12-minute video to encourage others to travel to the so-called Islamic State.

"We came to establish a state, we came to give our blood," he said.

The video was released overnight by the Islamic State's media wing, known as Al Hayat.

Prakash, who is of Fijian-Indian and Cambodian background, first appeared in an IS video in June last year but did not speak as he sat alongside other western fighters encouraging their followers to jihad.

That video ended with a photo of Prakash and stated that his story would soon be told.

In the most recent video, 23-year-old Prakash describes converting from Buddhism to Islam after visiting Cambodia with his family.

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The video also contained a chilling message for its Australian audience, although it's likely it was recorded prior to the weekend's counter terror raids.

"I also send a message to my brothers, my beloved brothers in Islam in Australia," Prakash said.

"Now is the time to rise, now is the time to wake up...you must start attacking before they attack you."

Terrorism expert Professor Greg Barton said the video followed a similar format to other Islamic State propaganda.

"It is mostly a positive message that turns dark towards the end and it's probably very effective at reaching its target audience," Professor Barton said.

"Even the lack of articulate poise on the part of Prakash probably makes it even more effective at reaching his peers, so it's quite disturbing on every level.

"He's clearly not an intellectual architect or a visionary, but I don't doubt he's quite effective at communicating with his peers and those slightly younger."

Prakash is critical of how Islamic State is portrayed in the western media.

"The media has portrayed that we come here, that we are social outcasts, because we had nobody we had to turn to Islam, because we were just trouble-makers in the past," he said.

"This is far from the reality."

After converting to Islam, Prakash attended Melbourne's controversial Al-Furqan Islamic Centre.

It is believed he left for the Middle East in 2013 and joined IS shortly after his arrival.

The Al-Furqan centre in South Springvale has also been linked to Melbourne teenager Abdul Numan Haider who was shot dead by counter terrorism officials in September 2014.

Prakash spoke about Haider's death in the video.

"My dear brother Numan [Haider], I knew this brother personally," he said.

"When he failed because the Government took his passport it did not stop him. Look what he did brothers, he rushed towards [paradise]."

Counter-terrorism officials are also investigating links between Prakash and the Melbourne teens arrested over an alleged Anzac Day terror plot.

Police said the five men arrested in Saturday's raids had attended the Al-Furqan centre.

Two men, 18 year-olds Sevdet Ramadan Besim and Harun Causevic, have been charged with conspiracy to commit acts done in preparation for, or planning, terrorist acts.