A former Sydney preacher who is now a senior figure of notorious terror group Jabhat al-Nusra has spoken out for the first time about why he joined the jihadi cause.

Abu Sulayman Muhajir fled to Syria at least two years ago and has found himself added to the most wanted list of Western intelligence agencies.

He started his association with extremist organisations when he became a mediator between two warring groups, Jabhat al-Nusra and Islamic State (IS).

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Former Sydney preacher Abu Sulayman Muhajir is a senior figure of al-Qaeda off-shoot Jabhat al-Nusra

But eventually he joined Jabhat al-Nusra.

Speaking from Syria's frontlines, Abu Sulayman warned Western forces to leave the Middle East.

'The choice is simple… leave our lands, stop interfering in our affairs or face perpetual war,' the Egyptian-Australian told SBS's Dateline from a secret location.

'They [the West] rob our resources, they back tyrants, they force regime change, and they economically enslave our nations.'

Abu Sulayman is best known for spreading his hate speeches throughout Sydney's west, most notably at the Al Risalah centre in Bankstown (above)

Abu Sulayman has spoken out for the first time about why he joined the jihadi cause after the death of Islamic State fighter Suhan Rahman, from Melbourne

Abu Sulayman - who is also known as Mostafa ­Mahamed - is best known for his hate speeches spouted across Sydney's west.

In one speech at Bankstown's Al-Risalah centre, the former preacher urged young men to spill their 'blood' in Syria, news.com.au reported.

He has also been threatened by fellow Australian Khaled Sharrouf who fights with Islamic State.

During the SBS interview, the senior leader said IS worked at 'delegitimising the rest of the Muslim community' by naming themselves as the 'exclusive bearers of Islam'.

On the other hand, he said Jabhat al-Nusra wanted to 'restore the right of the Muslim people to choose their leaders independently'.

They are one of the major forces battling the regime headed up by Syrian president Bashar al-Assad.

Abu Sulayaman said they also wanted to established a governing system based on Islam known as 'shura'.

Shura is the Arabic word for consultation, which according to the Koran is a beneficial practice.

After Rahman's death, his wife - known as Umm Jihad on social media - tweeted a photo of his dead body

Rahman was also friends with Mohamed Elomar - a Sydney boxer who fled to Syria to fight with Islamic State

Last year, Elomar was pictured on social media holding up severed heads and smiling at the camera

'Every society needs a penal code... we have a penal code in which punishments are appropriate to the crimes committed and act as a deterrent to others,' the extremist group leader said.

'Islam to us is whole and complete and that does include corporal and capital punishment.'

It comes as it is revealed the latest Australian to die in the conflict, Suhan Rahman, was a convicted criminal before her fled to the Middle East to fight for IS.

New details have emerged that Suhan Rahman was sentenced to 80 hours of community service for attempting to pervert the course of justice and witness intimidation in 2013, according to The Australian.

The 23-year-old, who was previously pictured with Sydney boxer-turned-terrorist Mohamed Elomar, also faced a number of charges including assault and unlicensed driving, where he was hit with a $1000 fine.