Inland Revenue staff in Upper Hutt had to be decontaminated after an envelope containing white powder was opened by a mailroom employee this morning.
The building, in Jepsen Grove, was evacuated about 7.20am, police said. Cordons were put outside the building to stop members of the public entering.
Sergeant Steve Dearns said staff were allowed to return about 9am after the package was removed and taken to ESR for forensic analysis.
Upper Hutt area commander Inspector Michael Hill said preliminary analysis suggested the powder was not a dangerous substance. But Inland Revenue staff who had contact with the package went through a Fire Service “decontamination process” as a precaution.
Police were investigating.