A 37-year-old Sydney man has been charged with sexually assaulting a 14-year-old girl on the Upper North Shore two years ago.

The girl allegedly met the man on the online chat site "Meet Me" in early 2015.

They then met at Montview Oval at Hornsby Heights on a number of occasions over the following 12 months, during which it is alleged she was sexually assaulted.

Detectives from the Child Abuse Squad released an image of the man they wanted to speak to and he handed himself into Chatswood Police Station on Monday afternoon.

He was charged last night with 12 counts of sexual intercourse with a person aged 14 to 16 and engaging in acts of child prostitution.

He was refused bail and is due to front Hornsby Local Court today.

Police said they became aware of the alleged assaults while they were investigating a similar case.

Child Abuse Squad Commander, Acting Superintendent Peter Yeomans, thanked the media and community for their ongoing assistance and support.