An exclusion zone has been set up around four containers at Napier's port after a chemical spill this morning.

Photo: Supplied / Napier Port

Firefighters were called to the port at 8.20am to investigate after a white substance was identified on the outside of the four containers, which were unloaded from a ship this morning.

Shift commander Mike Wanoa said sodium hydroxide, in a white powder form, had leaked from containers.

Mr Wanoa said firefighters in protective suits identified several other containers that were compromised and at risk of leaking the chemical, which is corrosive and potentially flammable.

He said firefighters were working on a plan to clean up the cordoned-off area, and there was no danger to the public.

The Fire Service was consulting with an expert in Australia on how best to clean it up.

The port said the containers have been placed well away from the harbour and there was no threat to marine life.

It said the incident was under control but may take several hours to resolve.