"Ashby probably did it himself. I've got no idea,"he said."I don't recall how I got back from[Parliament House cafe] Aussie's to here[his office]."

Mr Ashby called for a full investigation into the Wednesday night incident.

"As a member of staff to a senator,I respect the jurisdiction of the president of the Senate,"he said."To that effect,I have surrendered my pass.

"However there must be a full investigation of this matter,the allegations that proceeded the altercation and a range of other issues regarding the alleged treatment of female staff that may be relevant to this matter."

A One Nation staff member told the Sydney Morning Herald andThe Age on Thursday evening that Mr Ashby had already left Parliament to fly to Brisbane before Senator Ryan's decision.

The fight followed a series of sexual harassment allegations levelled against both sides of the spat:Senator Burston denied offering to"f---"a staff member to make her feel better,and retaliated by alleging Senator Hanson had twice sexually harassed him.

During a rushed appearance on Sky News on Wednesday night,Senator Hanson denied the sexual harassment claims Senator Burston directed at her.

"I might be 64 but I'm not that desperate. These are allegations that have been made up,there are no truth to them whatsoever and I feel sorry for his wife,I really feel sorry for his wife."

Senator Burston was elected as a NSW senator for One Nation in the 2016 election but abandoned the party in 2018,becoming the sole parliamentary representative for Clive Palmer's newly formed United Australia Party.

Wednesday's counter-harassment claims were triggered after Senator Hanson gave a speech under parliamentary privilege claiming a serving senator was being investigated for a case of"serious sexual harassment".

Queensland Labor senator Murray Watt described the day's events as"really disturbing"and"disgusting".

"It's a disgusting thing to do for a member of parliament to be smearing blood anywhere on the building,"he said.

"I would hope that the Senate president looks seriously at that and takes whatever consequences are warranted."