A motorcyclist has died on State Highway 1 north of Auckland.

The motorcyclist was the only person involved in a crash at the intersection of State Highway 1 and Bosher Road at Wellsford, 115km north of Auckland.

Fire Service northern communications shift manager Colin Underdown said it appeared the motorcyclist had a heart attack at the scene.

He said it was unclear if this was before or after his motorcycle crashed.

His death was the third on New Zealand roads this Easter, following a death in Otara, south Auckland last night and Morrinsville, northeast of Hamilton, earlier today.

It was unclear if it would count towards the official road toll if the heart attack had caused his death.

The accident has meant diversions are in place both ways at Wellsford, adding further to delays for northbound motorists out of Auckland after heavy traffic at the approaches to the new Silverdale-Puhoi toll road.

Slow-moving traffic tailed back up to 6km at the approaches to the toll road and tunnels. Motorists were advised either to be patient, or to take State Highway 16 via Helensville, and to watch for electronic signs to direct them to the best route.