Hamilton City Council is urging residents to be wary of a gang of rogue arborists claiming to work for the council.
Council staff were alerted to the group of men after they fleeced an elderly man of hundreds of dollars.
"A 93-year-old gentleman contacted us after he dealt with the group," HCC parks and open spaces manager Sally Sheedy said.
"Claiming to be working on behalf of council, they charged him $450 to remove branches from one of his trees which were hanging over the footpath."
The men said they worked for the council, but were not in a vehicle bearing a HCC logo and could not produce identification, Miss Sheedy said.
"They left after carrying out a pretty shoddy job, and cashed the gentleman's cheque within 15 minutes of leaving his property. We are horrified by this."
Hamilton Grey Power president Dave Collins was also worried.
"They're low people that do this and target elderly people that are perhaps a bit vulnerable."
He said he had not heard of the particular incident, but warned people to be alert.
Miss Sheedy said staff from the council's parks and open spaces unit had specific processes they worked through with residents.
"We would not turn up unannounced and carry out physical work on private property," she said. "If works were required, our staff would initially meet with the resident to discuss the work needed, they would be carrying council identification, and they would arrive in a council-branded vehicle."
Miss Sheedy said people should immediately contact the council and police if approached by anyone claiming to work for council, but unable to produce proof.