Northland power companies are warning people to beware of conmen posing as tree trimmers.
Top Energy and Northpower said the group of three men, described as Polynesian, were driving around in a white van pretending to be power company staff and demanding cash on the spot for felling or trimming trees.
The men have been telling householders their trees have to be cut back immediately.
The companies said it appeared some people have fallen for the frauds - but their own arborists do not cold-call or ask for money; they wear clearly branded protective gear and they drive vehicles with the Top Energy or Northpower logo.
The companies said anyone who had been approached by people asking for money to trim trees should phone the police immediately, and let their power supplier know as well.