Scammers are masquerading as the NSW Office of State Revenue and sending bogus speeding fines to consumers globally, as well as the revenue agency's own employees.
NSW Commissioner for Fines Administration Tony Newbury said he was first notified about the suspected phishing scam last October, but a recent surge in reports prompted him to issue a public warning.
At least 20 people have reported the scam in the past week.
"This scam is designed to trick people into paying money or giving out personal and banking information such as bank account numbers, passwords and credit card numbers," he said.
"Don't do it, don't respond or they could steal your money. Just delete the email."
The agency never sends fines by email - only on-the-spot or by post.
If a user clicks on link in the scam email, the agency's IT experts say a virus called cryptolocker will lock the computer and hold it to ransom.Even if the user pays money, the "key" may not work and identity information may be stolen