Former One Nation senator Brian Burston has Pauline Hanson, his former leader, of making unwanted advances towards him.

Mr Burston claims he left One Nation was partly because of sexual harassment from Hanson over two decades. 

“Right back when we had our first One Nation AGM at the Rooty Hill RSL [in 1998], that was the first time she hit on me,” he said, claiming she “rubbed her fingers up my spine” while listening to the national anthem and then propositioned him after he was elected in 2016 at her home in Queensland and Canberra.

Ms Hanson has dismissed the accusations.

Guardian Australia has also seen a complaint of sexual harassment made against Burston late last year, as part of a settled unfair dismissal claim. The complainant alleges he made an inappropriate advance on a distressed staff member.

A spokeswoman for Mr Burston denied that the senator propositioned the staff member. Mr Burston says the allegations were “garbage” and that Pauline Hanson was engaging in payback because he left One Nation.

And if it wasn’t ugly already, there’s more to come, as Mr Burston’s spokeswoman also said to expect a “bombshell” on Thursday evening in the Senate adjournment debate.