Action against Senator David Van was 'decisive'

In a letter to Victorian Liberal Party president Greg Mirabella seen by AAP, Senator Van said he could not remain a member of a party that "tramples upon the very premise on which our justice system is predicated".

"Given the Liberal Party's wholesale disregard for due process and natural justice in relation to allegations made against me, I write to resign my membership effective immediately," he said.

Senator McKenzie said Opposition Leader Peter Dutton's decision to immediately boot Senator Van from the party room and call for his resignation from parliament in the wake of the allegations was the right call.

"All political parties have faced these type of internal challenges over the recent past and for a leader to be so decisive, I think, was a testament to his strength of feeling around these matters," she told ABC's Insiders on Sunday.

"I think there was a lot of cheers silently across parliamentary offices with such decisive action being taken by a leader."

Senator Van denied the allegations and said he would co-operate with any investigation. 

On Friday, Mr Dutton confirmed further allegations had been brought against Senator Van.

Senator Van said he was "deeply distressed and hurt that I have not been afforded procedural fairness" in relation to the claims.

Senator McKenzie said she wasn't aware of specific allegations against Senator Van before they became public and she supported Senator Thorpe's decision to detail them under parliamentary privilege.

"Senator Thorpe was absolutely within her right to use parliamentary privilege to raise those issues as she did," she said.

Nationals leader David Littleproud said he was shocked by what had been alleged.

"I appreciate Senator Van wants to have a presumption of innocence but I also appreciate the fact Peter Dutton has the right to protect the Liberal Party and to undertake his own investigation," he told Nine's Today on Sunday.

"If his behaviour doesn't meet the standards of the Liberal Party, then (Peter Dutton) has every right to remove Senator Van from his party room and the Liberal Party has every right to accept his resignation."

Mr Littleproud hit out at Senator Van's decision to remain in parliament on the cross bench.

"While the senator can stay, under the law, really, he wasn't elected on his own volition," he said.

"He was elected on the Liberal Party. He wants to remove himself from the Liberal Party and then he should probably also remove himself from the Senate."

Indigenous Australians Minister Linda Burney said the events of the past week sent a bad message to the public.

"(Parliament House) should be a safe place to work, the parliament of any workplace in Australia should be safe," she told Sky News.

"Clearly there are still issues but I do not take away from the fact that much good work (on implementing reforms on workplace culture) has been done."

Senator Van's resignation came a day before the Victorian Liberal Party's administrative committee was to meet to further consider the allegations.

He was sworn in as a federal Liberal Party senator for Victoria in July 2019, with his term set to expire at the next election.

He is not expected to attend parliament on Monday, with the Senate holding its last sitting week before the two-month winter break.