Work' underway at Auckland's North Head in Devonport to maintain parts of the historic defence tunnels

Most of the tunnels will remain open during the process, however some will be closed from this week.

Meanwhile, the coastal track that runs around the base of North Head will be re-opened sometime in the New Year.

It's been closed since August after a large landslide.

Engineers have recommended scaling the cliff face of loose materials and removing dead vegetation to reduce risk of another landslide.

Work on the cliff face will begin early next year.