What's being billed as the largest phone scam ever reported in New Zealand could be costing the country $10 million.
The Ministry of Consumer Affairs says somebody pretending to be from a computer repair company cold calls people to say they have a virus, and tries to make them pay for software they don't need.
Scamwatch spokesperson Jarrod Rendle says based on scam reports and research, an estimated 30% of New Zealand adults have been phoned with this scam.
He says it looks as though one in 20 recipients are falling for it, losing an average of $200 each time.
"Based on the New Zealand population, up to $10 million dollars could have been swindled out of unsuspecting Kiwis."
He says people should spread warnings about the scam as far as possible.
"The message is simple: If someone calls you to say your computer has a virus or problem, it is a scam and you should hang up straight away."