Police said the victim and her two young children had just finished shopping at a supermarket in Portland on Thursday and were sitting inside their vehicle when an unknown man knocked on the driver's window at 1.10pm.

He then opened the door and stood in between the vehicle and the door so it could not be closed by the victim.

The man then made lewd, inappropriate comments while looking at the victim and touching himself in a sexual manner.

The victim told the man to go away before slamming the door and the offender then left the scene.

Police have released images of a man who they believe may be able to assist with their enquiries.

The man is perceived to be of Caucasian appearance, of a thin build, with brown hair tied back in a ponytail.

He was wearing blue jeans and a blue sweatshirt, with a tan coloured cap and a black face mask.

Anyone who recognises the man or with information is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au.

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