Prime Minister Scott Morrison announced on Thursday his department would look into allegations aired hours earlier by former press secretary Rachelle Miller.

"Given the seriousness of the claims made by Ms Miller, it's important these matters be resolved fairly and expeditiously," Mr Morrison told parliament.

"To this end, the minister has agreed to my request to stand aside while these issues are addressed by my department through an independent and fair process."

Former public servant Vivienne Thom will head the investigation as Mr Tudge, who "completely and utterly" rejects the allegations, goes on leave until Christmas.

"Ms Miller and I worked closely together in 2017. It involved constant travel, long hours and often we were under pressure," he said in a statement.

"We became attracted to each other and on a small number of occasions that attraction was acted upon.

"I have accepted responsibility for a consensual affair that should not have happened many years ago. But Ms Miller's allegations are wrong, did not happen and are contradicted by her own written words to me."

Ms Miller alleged her relationship with the minister was emotionally and, on one occasion, physically abusive.

"I'm fully aware that a year ago I said that my relationship ... was a consensual relationship," she told reporters.

"But it's much more complicated than that. I was so ashamed, so humiliated, so scared. I was exhausted. I told a small part of the story I was able to manage."

Ms Miller alleged Mr Tudge once physically kicked her out of a hotel bed, naked, one morning during a work trip because he was angry about being woken by her phone.

"He continued to kick me until I fell off the side of the bed and ended up on the floor," she said.

Ms Miller said she wants the government to listen to and acknowledge the experience of women in parliament.

"The Liberal party doesn't have a women problem, it has a men problem."

Ms Miller also chastised Labor for staying silent on the issue "because they have just as many skeletons".

"It's a sad reality that the perpetrators are the ones who must change the laws to make themselves accountable," she said.

Mr Tudge welcomed the investigation he said would consider Ms Miller's "contradictory written evidence" regarding her allegations.

"I regret having to say these things. I do not wish Ms Miller ill, but I have to defend myself in light of these allegations, which I reject," he said.

Employment Minister Stuart Robert will temporarily take over Mr Tudge's portfolios.

The new allegations against Mr Tudge come two days after a report by Sex Discrimination Commissioner Kate Jenkins detailing a culture of bullying and sexual harassment in federal parliament and politicians' offices.

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