A man accused of sexually assaulting a 13-year-old girl in a Melbourne cinema is being hunted by police.

Police have released CCTV footage of the man and are appealing to the public for information about his identity.

The teenager was watching a movie at a cinema on Springvale Road in Glen Waverley at around 4.40pm on February 20, when the man sat down near her, put his coat between them, then reached under the coat and assaulted her.

He fled when the girl's mother confronted him.

The man is believed to be Asian, in his 20s, of a medium to solid build and has black short hair.

At the time of the assault he was wearing tan pants, a blue zip up jumper and glasses.

Box Hill Sexual Offences and Child Abuse Investigation Team detectives hope releasing the image of the man leads to his arrest.