A man has suffered a broken jaw and broken teeth after falling 10 metres down an escalator guide rail at Sydney's Town Hall railway station.

He hit a metal pole after the fall, which occurred just before 11pm on Friday, and was taken to St Vincent's Hospital, where he remains in a serious but stable condition.

Police are looking for help in identifying a man who fell 10 metres down an escalator at Sydney Town Hall. Credit:NSW Police

Police attended the scene but were unable to immediately identify the man and released CCTV images to help locate his next of kin.

He has since been identified and police said he is a 21-year-old man from the Bankstown area.

Police are requesting that anyone with information relating to the incident contact Crime Stoppers on 1800 333 000 or at https://nsw.crimestoppers.com.au.