A teenage girl has been sexually assaulted in Sydney's west after going home with a man she met on a social media website.
Her alleged attacker is the third man to be arrested this week after allegedly using the internet to target youngsters, prompting police to issue a warning to parents.
Late last month, a 15-year-old girl told police she had been sexually assaulted in July by a man she had met on a social media website.
He allegedly chatted to the girl online and they met at Hurstville before he took her to a home at Carlton where it is alleged she was sexually assaulted.
The 24-year-old man arrested at a Villawood address on Wednesday was charged with aggravated sexual assault and refused bail to face Bankstown Local Court on Thursday.
In a separate attack, two teenagers contacted police earlier this year after they were targeted online and by mobile phone by a man requesting explicit photos.
A detective posing as a 14-year-old boy engaged the man in online and mobile telephone chats and police say a number of the conversations were sexually explicit and involved plans for the pair to meet.
A 34-year-old man was arrested at a shopping centre in Port Macquarie shortly after 10am (local time) on Tuesday.
He has been charged with two counts of using a carriage service to procure persons under 16 years for sexual activity.
It followed the arrest on Monday of a 27-year-old man accused of sexually assaulting a 14-year-old after befriending her on a social media website.
He allegedly made contact with the teenager online last month before inviting her to his Nelson Bay home, where he allegedly sexually assaulted her last week.
He has been charged with three counts of aggravated sexual assault and five counts of assault with act of indecency.
Police say parents should access their child's email and randomly check the contents.
Assistant Commissioner Mark Murdoch told reporters that parents needed to monitor the internet usage of their children.
"Parents need to take that responsibility because you don't know who your kids are talking to on the other side of the internet.
"These pedophiles purport to be other children, then when they arrange to meet, the kids are leaving themselves vulnerable."
