The girl sent a request on a video chat program on January 9 to connect to someone displaying the pop singer's photograph and birth date, police said.

Police said the Bieber impersonator then asked the girl to model "revealing clothing" during a video conversation.

Advertisement: Story continues below The girl told her mother, who called the police.

Commander of the State Crime Command's Sex Crimes Squad, Detective Superintendent John Kerlatec said posing as someone well-liked by children was typical behaviour for an internet predator.

"It's indicative of some of the grooming," Mr Kerlatec said.

"These people, they need to be liked, they need to be able to engage with other people and they will look at other people's vulnerabilities.

"In their world, if they don't have the characteristics to engage with someone ... they fail to lure someone into their net."

Mr Kerlatec said it was important for parents to be open with their children and educate them about using the internet, especially in the age of smart phones.

"We really can't sit with them all the time, so we've got to get them to ... understand what to do if there's something inappropriate."

The Justin Bieber impostor may be anywhere in the world, making this type of crime a challenge for police, he said.

"I think it illustrates that the internet has no boundaries."

Mr Kerlatec said police worked with interstate and international police to tackle internet grooming.

Police continued to investigate the Bieber impersonator incident, he said.

Police offered the following advice to teenagers and children:

- Check the settings on your social-networking page – change it so that only those you know and trust can see anything about you.

- Be aware that even if your settings are secure, your friends' settings may not, and this could leave you vulnerable.