A criminal gang purporting to be part of a network founded by infamous SuperMax inmate Bassam Hamzy has emerged in Sydney's upper north shore.

At least six young men claiming to be from the Brothers For Life gang allegedly visited Mohamed Mangal at Absolute Smash Repairs in Waitara several times in July and August, demanded $40,000 and threatened to set the business alight with him inside if he did not comply.

Held in custody: Mesbah Mirzaei.

They allegedly told Mr Mangal they were from Brothers For Life. However, police believe they have nothing to do with the on-again-off-again Bankstown gang founded by convicted murderer Hamzy in 2008.

Rather, they are part of a disturbing trend of young Middle Eastern men using the ''brand'' or ''banner'' of the gang to start their own unrelated criminal groups.