Social media sites including Twitter and Facebook will be monitored on election day to ensure electoral rules are not breached, Chief Electoral Officer Robert Peden says.
It is illegal to campaign on an election day, a prohibition which covers the publishing or broadcasting of anything intended to influence votes.
The Electoral Commission says the rules apply to social media sites including Twitter, Facebook and blogs - and any breaches will be followed up.
With tweeting becoming increasingly popular, Mr Peden says, the commission will keep an eye on electronic media communications on polling day, which is on 26 November.
"If people tweet on election day in a way which is trying to influence how somebody votes, then that's a breach of the act and we'll be following it up."
Mr Peden says the Electoral Commission will consider whether it needs to do anything more to ensure people are aware of the rules.
Labour Party MP Chris Hipkins says the only way ensure political comments are not posted on social networking websites on election day would be to completely shut down MPs' pages on them - which most would not want.
The MP for Rimutaka says political parties will have to ensure party members and helpers respect the rules.
However, Mr Hipkins says one danger is that if a politician posts a campaign message on their Facebook page before election day, supporters could post replies on election day - therefore making the post break the rules.
A senior lecturer in media and communications at Canterbury University says the Electoral Commission will have to explain to website users that the rules are there so people can vote on election day without being lobbied or harassed.
Dr Donald Matheson says it is important that people do not feel like the rules have 'Big Brother' overtones.