A large fire at an Auckland primary school is being treated as suspicious, the fire service says.

An entire block at Richmond Road School, in Ponsonby, went up in flames early this morning.

Fire-fighters were called to the scene around 5.50am.

"It was quite a significant fire," said northern communications shift manager Tania Matthews.


"There was an entire school block well involved [when fire-fighters arrived]."

Fire investigators are at the scene, but Ms Matthews said it is already being treated as suspicious.

No-one was injured in the blaze, however it is believed the fire caused serious damage to the school.