Australia's first publicly accessible register of child sex offenders has been published online in the state of Western Australia.
Initially, the details available include photographs, names and physical descriptions of nine sex offenders the police have lost track of.
Parents will be also able to enter their addresses to see if there are any convicted paedophiles living nearby.
But there are concerns about possible vigilantism and mistaken identity.
The Western Australia government describes the register as a balancing act between community safety and the ability of the police to manage convicted paedophiles, says the BBC's Duncan Kennedy in Sydney.
But legal groups have questioned how useful it will be and raised concerns about the potential for vigilante attacks.
The Criminal Lawyers' Association said that authorities would find it hard to stop the pictures being illegally posted elsewhere on the internet.
But the government says it is an offence to republish any information from the site and said any reprisal attacks would not be accepted.
This site is supported by Grant/ Cooperative Agreement No. 1UF2CE002359-04 from the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention.