A teenage girl who met a man online and went on to meet him several times for sex at a Sydney oval has identified a man who may go by the name of Alex.

Police are attempting to identify the man involved, who is described as being Asian and aged in his mid twenties or thirties.

He is clean shaven, wears glasses, and also wears business-style clothes, police said.

The man began speaking with the then 14-year-old girl online in early 2015, before meeting her at an oval in Hornsby Heights for sex on several occasions between February 2015 and January 2016.

Despite extensive inquiries, detectives from the Child Abuse Squad have not been able to identify the man involved.

Acting Superintendent Peter Yeomans urged people to look closely at the image to see if they could recognise the man involved.

He also reminded parents to speak with their children about online safety.

 "Any app, on-line game, or social media platform that allows the user to be in contact with someone they've only met online potentially puts them at risk," Detective Yeomans said.

"Not only should young people be very careful about providing personal details to a person they only know in online environment, they should never organise to meet as doing so may place them at further risk of harm."

Anyone who may have information about the man pictured should contact Crime Stoppers on 1800 333 000. 

Fairfax Media