Gwent Police are appealing for witnesses following a collision between a van and an e-bike in Llantarnam.
The man who was riding the bike has been taken to hospital with serious injuries.
A driver of a red van, believed to have black side windows, silver alloys with yellow and red chevrons on the back, reportedly left the scene following the collision.
The road is currently closed in both directions from Llantarnam Way roundabout to the lights near Malthouse Lane.
Enquiries are ongoing and officers are appealing for anyone who may have seen the collision, have dash-cam footage of the area at the time, or has any information which could assist the investigation, to come forward.
Anyone with information is urged to call us on 101, quoting log 504 of 10/01/24, or send us a direct message on social media.
Alternatively, you can call Crimestoppers anonymously on 0800 555 111.
Appeal to locate Herefordshire man who failed to appear at court
Traders frustrated as road closure extended
Wins for local firms among new highways contracts
Hereford restaurant seeks licence again
Scam websites posing as Hereford firm shut down
Farm plans fourth poultry shed
Free 30-minute parking scheme launches in Herefordshire
Prolific shoplifter jailed for Herefordshire offences