Police have released images of a man wanted over a sexual assault on a bus at Thornbury.

The incident happened on November 16 last year.

The man, described as Caucasian and aged in his 40s, is alleged to have sat next to a 24-year-old woman, touching her inappropriately, prompting her to yell out.

Anyone who recognises this man or who may have witnessed this incident is urged to contact Crime Stoppers on 1800 333 000 or submit a confidential report online at www.crimestoppersvic.com.au