Scammers have pocketed more than $1 million from two Northern Territory businesses in recent months.
In September a building company lost more than $550,000 after it was transferred to a fraudulent bank account as part of an email scam.
While in October another business lost more than $530,000 in a similar fashion.
Detectives from the police cybercrime unit are investigating both incidents but don't believe they are connected.
However, police say there have been a number of scams in recent weeks targeting the building and real-estate industries.
Senior Constable Nadine Caulfield said scammers could be very good at impersonating accounts and email addresses.
"If you are planning on transferring a large amount of money online, police recommend contacting the recipient directly in order to confirm payment details," she said.
"If you fall victim to online crime, we encourage you to report it to police."