An elderly woman with a walking frame has been sexually assaulted at a railway station in Melbourne's south-east.

The 87-year-old woman was waiting for a train at Aspendale about 11am when a man asked her if she wanted money.

CCTV images of a man wanted over the sexual assault of an elderly woman at Aspendale Railway Station. Credit:Victoria Police

When she declined, the man kissed her on the cheek and sexually assaulted her, a police spokeswoman said.

The woman managed to break free and boarded her train.