Emergency services are responding to a diesel spill and a three-vehicle crash blocking the northbound lanes on State Highway 1 north of Auckland, causing lengthy delays.

Police said they are currently on the scene assisting firefighters after the diesel created a slick over the highway near Ōrewa.

All northbound lanes were currently blocked after a three-vehicle crash about 12.18pm, which was adding to the delays in the area.

At this stage, one person had suffered injuries, a spokesperson said.

Police were advising motorists that both northbound lanes were closed from the Grand Drive off-ramp and traffic was being diverted.

“Motorists are advised to expect delays and seek an alternative route or delay travel if possible,” police said.