It's believed the 70-year-old man 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 police are urging anyone with information to call Crime Stoppers on 1800 333 000 or visit the website: https://nsw.crimestoppers.com.au/