Detectives on Sydney’s northern beaches are urging extra vigilance after a teenage girl was allegedly approached and assaulted by an unknown man at Frenchs Forest.

The 13-year-old girl left a friend’s house and began walking home along Poulton Road about 5.30pm yesterday (Thursday 9 June), when the man appeared from behind a parked silver-coloured, two-door car.

The man allegedly spoke with the teenager before grabbing her right arm and shoulder.

The girl managed to break free from the man’s grasp before running home, the alleged offender close behind.

She reported the incident to her mother and police from Northern Beaches Local Area Command were alerted and commenced inquiries.

A canvass of the surrounding neighbourhood was conducted in a bid to identify any potential witnesses to the alleged incident.

The man has been described as being 25-30 years old, of Maori/Pacific Islander appearance with a dark complexion, short curly brown hair and brown eyes.

He was wearing a long-sleeve shirt and denim jeans at the time of the alleged incident.