A Federal Labor politician has called an ABC reporter a "maggot" while trying to shield embattled MP Justine Keay from reporters.

Key points: Labor politician Brian Mitchell apologises after calling journalist a maggot

Labor politician Brian Mitchell apologises after calling journalist a maggot Lateline reporter Matt Wordsworth was quizzing embattled MP Justine Keay

Lateline reporter Matt Wordsworth was quizzing embattled MP Justine Keay Mr Mitchell tried to shield Ms Keay from answering questions on dual citizenship

Ms Keay was a British dual-citizen at the last election but is refusing to refer herself to the High Court.

At a barbeque at Parliament House on Wednesday, fellow Tasmanian Labor member Brian Mitchell tried to physically block an ABC cameraman before sniping at reporter Matt Wordsworth.

"Go and do your research, maggot!" Mr Mitchell said to the Lateline reporter.

"Ask the right question, don't be prejudicial, don't use prejudicial language."

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When Mr Wordsworth asked Ms Keay when she was chosen as Labor's candidate for Braddon, Mr Mitchell said: "What's that got to do with it?"

"The High Court has previously said ... that if you take reasonable steps that's grounds to meet what's required under section 44," Mr Mitchell said.

"She's answered all this."

Ms Keay was preselected in June 2015 but did not send paperwork to the Home Office until May 2016.

UK authorities only registered her renunciation on July 11, 2016 — nine days after last year's election.

Mr Mitchell was a journalist and newspaper editor in Western Australia for more than a decade before being elected as the Member for Lyons last year.

After making his comments, Mr Mitchell told Parliament he had called Mr Wordsworth and apologised.

"Earlier today I saw some vision on ABC TV which included some heated words from myself towards a press gallery journalist," he said.

"I respect the work, in fact deeply respect the work, that Mr Wordsworth and all his colleagues in the press gallery do, and they should be free to do it without fear or favour."

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Liberals seize on 'outrageous attack'

The Minister responsible for the ABC, Mitch Fifield, said Mr Mitchell's behaviour was appalling.

"Journalists doing their job should not be subjected to abuse," the Communications Minister said on Twitter.

Tasmanian Liberal Senator Eric Abetz said it was an "outrageous attack".

"Brian Mitchell's ugly and bullying comment and the silence from his other Tasmanian Labor colleagues is indicative of the Labor culture," Senator Abetz said in a statement.

"Mr Shorten needs to pull his whole Tasmanian Labor team into line."

The Media, Entertainment and Arts Alliance said it was "unacceptable behaviour towards an accredited journalist".

Union CEO Paul Murphy tweeted: "Abusing a journalist doing his job. An absolute disgrace."

Braddon MP Justine Keay says she has taken the steps she needs to. ( Facebook: Justine Keay MP )

Justine Keay says eligibility is 'rock solid'

When Ms Keay was allowed to answer, the Braddon MP said she took, "every single step I needed to".

"The date you post your documents … to the Home Office is the date that you have actually renounced your citizenship," she said.

Earlier on Wednesday, Ms Keay said her eligibility was "rock solid" and referring her to the High Court would be unreasonable.

"The cloud that has come over me is a pure fabrication of the law by people like Eric Abetz and Malcolm Turnbull," she told ABC Radio Hobart.