The organization warns that the use of non-approved knock-off chargers isn't without danger, there are quite a number of reported cases where such chargers turned the hardware they were charging into a smokey melted lump or even started a fire.
Many times a simple charging process has turned a piece of hardware into a smokey melted lump and on some occasions more damage has been done.Source: The Inquirer
However "more damage" is not strong enough to describe the incident in New South Wales that has prompted the warning from Australian Fair Trading commissioner Rod Stowe.
Stowe, reacting to a report that a knock-off charger started a fire that killed a woman, said, "These devices pose a serious risk of electrocution or fire," and recommended that no one buy or sell them.