Police in Christchurch say there has been an increase in the number of people posing as officials and emergency workers since the earthquake.
Senior Sergeant Phil Dean says the imposters have been claiming to be officials from local organisations and government departments.
There are also reports of people impersonating police officers, some of them reportedly wearing clothing that looks like official stab-proof vests and police caps.
Mr Dean says in one particularly disturbing case, a person purporting to be an officer tried to order people from their homes claiming there was a gunman in the area.
He says the offender was found to have two air pistols and has been charged under the Arms Act.
Mr Dean says that if members of the public have any doubts, they should ask for identification.