Mert Ney sydney stabbing
Mert Ney being detained by police in Sydney (Image: AAP)

Mert Ney, the man who allegedly committed a knife attack in Sydney on Tuesday, poses a problem for the Australian media.

Ney has a documented history of mental illness and drug abuse, and reportedly left a psychiatric facility just days before the attack. But he also yelled the Arabic phrase "Allahu akbar" while brandishing a knife, instantly creating feverish speculation about possible links to radical Islam.