Liberal Senator Linda Reynolds has threatened to sue Brittany Higgins for defamation.

Higgins revealed this week that she had received a concerns notice from her former boss after posting criticism of her on Instagram.

A concerns notice advises a person who is alleged to have made defamatory statements to make amends to avoid legal action.

It does not mean that any legal paperwork has been lodged or that the person will proceed with a legal complaint.

“I’m considering my legal options,” Higgins said.

Reynolds released a statement confirming the conerns notice had been sent and lamenting that Higgins had made the “private communication” public.

“Ever since Ms Higgins first made her allegations of rape public, I have been the target of unwarranted criticism and abuse,” the Senator said.

“Despite her repeated defamation of my character, until now I have not taken any action against her personally – even though I considered her words to breach our previous settlement agreement.

“Yesterday Ms Higgins made yet another defamatory post about me. I have had enough. I will not tolerate being defamed by her or anybody.”

Reynolds was Higgins boss when Higgins claimed to have been sexually assaulted in a ministerial office.

Liberal staffer Bruce Lehrmann was charged with rape but never convicted and maintains his innocence.

Higgins later received a reported $3m payment from the Federal Government as compensation for not having been properly supported.

In an Instagram post this week, Higgins complained about Senator Reynolds plans to refer her compensation payout to the National Anti-Corruption Commission.