A young girl has been sexually assaulted at the movies in Glen Waverley.

Police say a man – believed to be about 20 – walked into the cinema at The Glen on Springvale Road at about 4.40pm on Saturday, February 20.

He sat two seats away from a 13-year-old girl – placed his jacked between them – and sexually assaulted the girl under the jacket.

The girl’s mother confronted him, before he fled as she went to report the disturbing incident to cinema staff.

A clear CCTV image has been released of the suspect, believed to be about 20 and wearing a blue hoodie and tan coloured pants.

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