It's believed the 70-year-old man from the Wollongong area veered off Oallen Ford Road, Oallen - about 85km east of Queanbeyan - and down an embankment at about 3.30pm on Wednesday.

His friend, along with a passerby, administered first aid until emergency services arrived at the scene.

Officers from Monaro Local Area Command have begun inquiries into the incident and are preparing a report for the coroner. At this stage police are not aware of any contributing factors to the accident.

Police are urging anyone with information to call Crime Stoppers on 1800 333 000 or visit the website: https://nsw.crimestoppers.com.au/