Users of free wifi are being warned to take precautions to avoid having their phones and laptops hacked.
Internet watchdog Netsafe says people shouldn't make any sensitive transactions, for example online banking, using free wifi.
Chief technology officer Sean Lyons says users should be aware security protocols can vary greatly.
"With poor security on the wireless device that you connect to, you can almost be transmitting what you're doing globally to anybody who just happened to be passing with the right kind of tools and wanted to take a look at what it was you were doing. "
Netsafe says while there are precautions users can take, the Government should look at some form of regulation if the industry proves irresponsible
Wifi providers are legally required to assist law enforcement agencies and advise of any copyright infringements, but the law does not require them to provide secure networks.
The Labour Party says the Government should consider law changes to require businesses to ensure their free wi-fi networks are secure.
The Government says while it's responsible for its own systems, individuals have to take responsibility for their own security.