Shonky tree loppers are taking advantage of people affected by the recent NSW storms, offering to help for a fee they say will be repaid by the SES or insurance companies.
"The SES has confirmed this is a scam," NSW Fair trading commissioner Rod Stowe said.
"They have not engaged any contractors to undertake work on behalf of the agency, and they have also notified NSW police of these reports."
Mr Stowe is urging people around the Blue Mountains and Sydney's west, some of the worst-hit areas in the storms on Friday and Saturday, to beware of the bogus tradesmen.
"Avoid cold-calling and unlicensed repairers," he said.
Warnings about the scam come as SES volunteers work to repair roofs and clear fallen trees at 300 properties across NSW, mainly in Sydney's west.
More than 1000 calls for assistance were received by the SES following the storms with driving rainfall smashing Sydney's west and northwest.
Crews also conducted about 20 rescues of people, most of whom ran into trouble while driving across flooded roads.
Power was cut to more than 50,000 homes and businesses across Sydney during Saturday's foul weather but on Sunday morning Endeavour Energy said, of its 25,000 customers who lost their connection, only about 1300 remained without electricity.