A large diesel spill - spanning 20km of road - is threatening to close a highway in the South Island this morning.
The spill on State Highway 6 between Nelson and Blenheim, stretches between Central Rd and Hori Bay Rd.
It's believed to be around 20km long, police said.
Police were en route to the scene to assess the situation at 9.20am, while the local council had also been called in.
The road is still open at this stage, police said, but may need to be closed later while the diesel is mopped up.
