Diversions are in place on State Highway 1 at Ātiamuri after a truck and trailer unit rolled overnight.

Emergency services were called shortly after midnight.

The crash happened between Tirohanga and Chestnut roads, says a police spokesperson.

"Heavy lifting equipment has been needed to right the truck and trailer and the road is not expected to reopen until 8am.

"The sole occupant of the truck received serious injuries and was airlifted to hospital.

"Police and the Commercial Vehicle Safety Team are investigating.