One Nation leader Pauline Hanson is challenging a court’s decision ordering her to pay $250,000 for defaming Brian Burston despite the former senator having sexually harassed his staff.

Her appeal, launched on Monday, takes issue with an October 19 decision by Federal Court Justice Robert Bromwich finding Ms Hanson defamed Mr Burston through “seriously damaging” comments made on Nine’s Today Show in March 2019.

On the Today Show, Ms Hanson falsely claimed her former One Nation colleague had sexually abused a female colleague and had assaulted the party’s chief of staff James Ashby without provocation in the Great Hall of Parliament.

“I find that both [imputations] were seriously damaging to Mr Burston’s reputation, being broadcast on a nationally broadcast television program watched by over 290,000 people at the time. They were both false,” the judge said.

However, the judge found Mr Burston sexually harassed staff in his office, harassed a female staffer, and brought the senate into disrepute through his shocking behaviour.

Justice Bromwich called Mr Burston’s conduct “objectively wrong and inappropriate”, including that he told staffer Wendy Leach, “Oh Wendy, you probably just need a good f***”.

“Mr Burston had apparently not kept up with changes in society in relation to the rights of women, with the tide having turned even more decisively in recent years, most particularly in relation to the conduct of and around elected representatives and their staff,” the judge wrote.

The 74-year-old had sexually propositioned Ms Leach and had sexually harassed another staffer Terri-lea Vairy, the judge found.

In November 2020, Ms Hanson also filed a counter-suit claiming Mr Burston’s defamation case and sexual harassment allegations made against her amounted to sexual discrimination.

This case is ongoing.

Mr Burston quit Ms Hanson’s One Nation to join United Australia Party in June 2018 after falling out with his former colleagues over his stance on then prime minister Malcolm Turnbull’s proposed tax cuts.

He failed to retain his seat at the 2019 federal election.

A date for the appeal hearing has yet to be set.