National MP Tau Henare is defending himself after he called a young select committee submitter a liar.
James Sleep, a teenage unionist and left-wing blogger, gave evidence before the transport and industrial relations committee last month.
Mr Henare said Mr Sleep was lying when he was telling the committee about a worker fired under the 90-day legislation.
Mr Sleep later described Mr Henare's actions as bullying.
Labour MP Carol Beaumont said Mr Henare should apologise and all submitters should be treated with respect.
"They are doing our democracy a favour by coming along and frankly with a young submitter like James Sleep it's even more important that we listen."
If Mr Henare believed there was a mistake in the submission he should have asked for clarification, Ms Beaumont said.
"He immediately leapt into it as if it was a lie instead of just saying, hang on, can we just clarify this for me."
Mr Henare defended his actions today. He told media he did not believe Mr Sleep was telling the truth and had questioned him about it.
"I just told him to bugger off, that's all.
"If you're going to give a submission, and you're going to read your submission out, and select committee people are going to follow it word by word, you shouldn't change it."
Mr Henare said Mr Sleep might learn from the experience.
Council of Trade Unions secretary Peter Conway wrote to committee chairman David Bennett complaining about the incident on behalf of Mr Sleep.
Submitters are generally listened to attentively when they participate in the democratic process.
Former ACT MP David Garrett came under fire when he threatened prison officers who had criticised private prisons at a select committee.
He said they had damaged their job prospects. Labour and National MPs on that committee assured the prison officers they had the right to speak their minds before a parliamentary select committee.