A 52-year-old man has been charged with sexually assaulting a 13-year-old girl at a boarding house in Sydney’s south.

It’s believed the popular Northern Beaches busker struck up a conversation with the girl, who he didn’t previously know, at Manly on Monday.

He allegedly gave her an alcoholic drink and travelled with her on public transport to a Rosebery boarding house.

Police are refusing to say what type of boarding house it was but it’s not believed to be part of a school.

The man was questioned on the way, reportedly telling a member of the public the girl was his daughter.

He allegedly raped the teenager in the boarding house.

The man was arrested outside a home in Rosebery on Thursday, where detectives also seized several items for forensic examination.

He’s been charged with two counts of aggravated sexual assault of a victim under 16, and four counts of intentionally sexually touching a child between the ages of 10 and 16.

Police refused him bail ahead of a court appearance today.