A post shop near the prime minister's Huapai electorate office was shut down on Tuesday in the seventh white powder scare in the past week.
A worker at Kumeu post office spotted white powder leaking from an envelope.
It was addressed to Prime Minister John Key. The worker was sorting mail into post office boxes at about noon.
A Defence Force spokesman says the substance was found to be harmless and a cordon around the site was removed shortly afterwards.
He says the package was a hoax and contained an inert substance.
Police and a Fire Service Hazardous Materials team were called to decontaminate the postal worker and the scene. The powder will be tested.
Police investigations are continuing to establish if the incident is linked to other recent white powder events.
Packages were last week sent to the offices of MPs Peter Dunne, Gerry Brownlee and John Banks as well as the French Embassy and the Grey Base Hospital.
On Monday the Health Ministry offices on The Terrace in Wellington were evacuated after a white powder was sent in a letter to the ministry.
It was later found to be innocuous.
- © Fairfax NZ News
Should we raise the retirement age?