Palmer to sue Brough for defamation

Liberal National Party candidate Mal Brough has brushed off mining magnate Clive Palmer's threats to sue him for defamation before the September 7 election.

Mr Palmer has vowed to begin defamation proceedings against Mr Brough, who is contesting former speaker Peter Slipper's Sunshine Coast seat of Fisher.

Mr Brough says he's not overly concerned.

"One of Clive's hobbies is litigation. I'll leave it at that," he told AAP on Wednesday.

The legal threat by Mr Palmer, who's leading his own party into the poll, continues to highlight Mr Brough's involvement in a sexual harassment case lodged against Mr Slipper by former staffer James Ashby.

The case was thrown out in December by Federal Court judge Steven Rares, who said Mr Ashby had "pursued a political attack" against his former boss "in combination" with others, including Mr Brough.

Earlier this month, Mr Palmer claimed Mr Brough once asked him to fund a campaign aimed at destroying Mr Slipper's reputation.

Mr Palmer claimed that during a meeting at his Coolum Resort in April 2012, Mr Brough outlined Mr Ashby's potential sexual harassment case.

Mr Brough denied Mr Palmer's allegations and accused the Palmer United Party founder of longstanding inconsistencies around the issue.

On Wednesday, Mr Palmer said he would sue Mr Brough for defamation before polling day for effectively calling him a liar.

"I've got the evidence which I'll produce in court which tells you who is telling the truth," Mr Palmer told reporters.

Asked when he will lodge legal proceedings, he said: "As soon as we can. Certainly before the election."

Mr Palmer said Mr Brough should not have been endorsed as the LNP's candidate for Fisher.

"Tony Abbott has disendorsed people for having things on their websites but he doesn't seem to disendorse people who have serious allegations confirmed by the federal court," he said.

"That seems very strange to me."