A man accused of critically injuring a road worker by striking them with a vehicle, in Waikato - is facing numerous charges

A white SUV drove at speed through a work site on Waharoa's Dunlop Road at mid-day yesterday - despite safety measures in place.

Police believe the driver was involved in an altercation at a nearby business just before.

It's alleged he threatened and assaulted staff before driving off.

Police are appealing for witnesses.