Authorities are investigating whether New Zealand should follow California's lead and make it a criminal offence to impersonate others including politicians on the internet, notably via Twitter and Facebook.

California has passed legislation making it a crime to "harm, intimidate, threaten or defraud" through the internet or other electronic means. The offence carries a fine of up to US$1000 ($1350), a year in jail or both.

"Our identity is one of the most personal things we have, and when someone misuses that it seems there ought to be some sort of deterrence," the law's author, State Senator Joe Simitian, told BBC News.

Senator Simitian's legislation updates century old laws written when "no one could have anticipated Facebook or Twitter or even email - all of which are ripe for the kind of online impersonation this bill seeks to address".

The Privacy Commission recently highlighted the Californian legislation, and Assistant Privacy Commissioner Katrine Evans yesterday told the Weekend Herald the issue was among several being considered by the Law Commission.

The Privacy Commission would have input into that work.

The commission had some concerns about online identity impersonation but wanted to hear from the public to learn how much of a problem it was.

Ms Evans urged those affected by identity impersonation to complain to the commission.

She also advised people to do "vanity searches" on their own names to monitor what was being posted on the internet in their name.

Political blogger David Farrar said politicians - including Labour leader Phil Goff, Labour MP Shane Jones and Energy and Resources Minister Gerry Brownlee - had been targeted by online impersonators.

"There probably does need to be some sort of offence for serious impersonation buy I think it's very important to recognise the difference between parody and serious impersonation," he said.