Emergency services are at the scene of a significant diesel spill on State Highway 1 near Taupō.
A police spokeswoman said they received a call from a driver about 2.30pm to say his truck was leaking diesel about 1km south of the intersection with Link Rd.
The truck had leaked a "significant amount", she said.
The fire service is on scene helping to hose down the highway and police are helping with traffic management.
The road is still open, she said.