Motorists traveling on State Highway 2 are being diverted at Karangahake Gorge following a slip.
The gorge is east of Paeroa, in Waikato.
A police spokesperson said the slip was fully covering the east bound road between School Rd and Waitawheta Rd.
Traffic had been turned away since the slip happened at 12.30pm.
Fire and Emergency New Zealand and police were managing traffic while work was undertaken to clear the slip by contractors.
The NZ Transport Agency said the slip would take most of the day to clear and advised drivers to allow an hour for detours.