Police are investigating a suspicious fire at a west Auckland primary school early this morning.

The blaze at the near- new classroom at Green Bay Primary School was well involved when firefighters arrived at the scene just after 4.30.

Detective Sergeant Kelly Farrant says more than 60 children need a new classroom, and many have lost valuable schoolwork.

Police have released pictures of two scooters, one with blue detail and one with pink.

They say anyone who was in the area and saw something suspicious around 9 last night should get in touch.