Independent MP Peter Dunne says he does not know what the motive could have been for someone to send white powder to his electorate office in Wellington.
Mr Dunne, the MP for Ohariu, and government minister Gerry Brownlee were sent the envelopes on Thursday, prompting police, the Fire Service, ambulances and the army to respond. The substance was later identified as baking soda.
One envelope was opened by a parliamentary staff member in Mr Brownlee's parliamentary office, while the other was opened by a staff member at Mr Dunne's electorate office in the northern suburb of Johnsonville. Both offices were cordoned off by police until the army arrived.
Mr Dunne said he understands that the package arrived in the morning mail.
Children from a creche at a community centre and blood donors at a mobile unit near Mr Dunne's office also had to be evacuated.
Johnsonville Community Centre administrator Christine Ritchie said 23 children stayed in the mobile unit until their parents came and picked them up. She said she was pleased that emergency services took the action they did.
Wellington area tactical response manager Senior Sergeant Hamish Milne said police are taking the hoax seriously and it they catch who is responsible they will be charged with wasting police time.