MPs share some of their less favourable tweets.

Members of Parliament have fronted up to their online critics, responding to Twitter comments ahead of a controversial cyber-bullying bill becoming law.

MPs said the insults they received were generally not at the level of those intended to be caught by the law, although they could be quite personal.

They agreed to share some of the worst they had received to highlight that often-anonymous keyboard warriors were directing their vitriol towards real people - albeit ones with thicker than average skins.

Hagen Hopkins There are plenty of jokes about Peter Dunne's hair on Twitter.

New cyber-bullying law

The Harmful Digital Communications Bill is poised to pass, with all parties except ACT supporting the provisions to crack down on online harm.

The bill was introduced in the middle of public outcry over the self-titled Roast Buster group, Auckland teenage boys who boasted online about having sex with drunk and underage girls.

It will create a new offence of sending messages or posting material to cause harm, punishable by up to three months in jail or a $2000 fine.

Inciting someone to commit suicide will also carry a maximum three-year jail sentence.

Harmful digital communications could include emails, texts and social media posts used to intimidate others, spread damaging or degrading rumours, and publication of invasive and distressing photographs.

Communications Minister Amy Adams said things could go viral on the internet very quickly, damaging people's reputations and their mental health.

Internet service providers or other entities like Facebook, Twitter or Google could be asked by a New Zealand agency to remove a harmful communication.

But critics of the bill say it will limit free speech, and could criminalise children with harsh penalties.

ACT Party leader David Seymour is the only MP not supporting the legislation, as he believes it is overly broad and could criminalise young people.

"Ordinary internet users, especially young people, could fall foul of the law's criminal provisions for minor missteps."

It was the first time Seymour had voted against Government legislation, but he said he was concerned it would be "an overly broad, unenforceable piece of legislation which countless ordinary people would inadvertently breach every day."

UnitedFuture leader Peter Dunne had had similar concerns, but had been reassured after speaking with Adams, and planned to support the bill.

Labour was "reluctant" in its support of the bill, with communications spokeswoman Clare Curran saying in Parliament on Tuesday the party still had significant concerns.

The bill is set to clear its final hurdle after returning to Parliament on Thursday, but time may run out before it can be voted on.