Extra students are pressuring the roll, resources and planning at New Zealand's biggest school.

Education Ministry data shows student rolls grew by nearly 16,000 pupils in the past year, and it says immigration is largely the reason.

Rangitoto College Principal Patrick Gale says the school zone has had a lot of infill housing in the past few years.

"And that's leading to higher population density, but the families that are choosing to move into those homes are often immigrants- so those two are inter-connected."

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