Fake fundraisers have been trying to exploit the good name of Coastguard Bay of Islands to part people from their money.
The cold-calling scam has angered Coastguard volunteers, who say it could damage the group's hard-earned reputation as well as depriving real charities of money.
Coastguard Bay of Islands president Maureen Calkin described the phone calls eliciting donations as ''bloody cheeky''.
It was not known how many people had been called, or if the scammer had managed to get any money, but three calls had been reported to the organisation in recent weeks by people whose suspicions were aroused.
All calls were to homes in the greater Kerikeri area.
Calkin said Coastguard Bay of Islands, like any charity, always needed more money but never used cold-calling as a fundraising method — so any phone call asking for cash and purporting to be from Coastguard Bay of Islands was a scam.
The same was true for Coastguard Northern Region and Coastguard New Zealand, she said.
There was nothing distinctive about the caller's voice or accent but it appeared to be someone with local knowledge, because the scammer knew the engines on Coastguard Bay of Islands' rescue boat were currently being repaired.
Calkin said the group had not asked the public for donations to help pay for the engine repairs.
Instead the work was being funded by the group itself and by Coastguard Northern Region.
The scammer had asked for donations by internet banking but hung up when pressed for a contact name or phone number.
Russ Devin, a Coastguard volunteer since 2005, was angry that someone would try to exploit the group's good name for their own profit.
''Anyone who does that is scum really. And that's the nicest word I can think of.''
■ Have you been called by someone claiming to be from Coastguard Bay of Islands and asking for money? If so contact Kerikeri Police on (09) 407 9211, the Advocate's Kerikeri office on (09) 407 3287 or firstname.lastname@example.org.