Former foreign affairs minister Marise Payne has told a court Brittany Higgins’ alleged rape in Parliament House was a devastating, incomprehensible and appalling act.

Payne, a former senator, was giving evidence in Senator Linda Reynolds’ defamation trial in the Western Australian Supreme Court against Higgins.

Reynolds is suing Higgins, her former staffer, over social media posts that the Senator claims damaged her reputation.

On Tuesday, Payne said she was “significantly concerned” by Higgins’ alleged sexual assault and her allegations against Reynolds after it became public in 2021.

“Concern as a senior member of the government, concern that such alleged events might have taken place in the parliamentary workplace, and concern that a young woman who had been part of the staffing team,” she said.

“It was almost incomprehensible to me that such an appalling act could have taken place in our federal parliament.”

Payne said she was also worried for Reynolds after Higgins’ allegations about the Morrison government’s response to the 2019 incident.

“[Reynolds] had a long-standing reputation for her interest in and support of women’s participation in the political process … any issues which raised questions about her commitment and her level of commitment in that way would obviously be concerning for her,” she said.

“The serious nature of the allegations made about the events of some years prior would be enormously distressing to hear.”

Payne said her friend and colleague of 30 years was put under an “enormous amount of pressure” in the Senate chamber in the following days.

“She was so distressed and so upset by the assertions being made about her that she was struggling to represent and to respond to those questions as she previously would have been able to,” she said.

“Knowing that some of the material was being misrepresented, in her view, made it even more difficult.”

Payne said Reynolds had “physical trauma … a combination of shaking and what I regarded as elevated breathing”.

“That was most unusual for the woman that I had known for three decades,” she said.

Payne said she became “very concerned” about Reynolds’ “wellbeing and the state of her health and the impact that [the political] attacks were having on her”.

“It was deeply disturbing, deeply troubling to see your friend and colleague appear in such a situation, and I think that was the overwhelming view of the majority of our friends and colleagues across the Coalition party room,” she said.

She said Reynolds was sometimes in “depths of great despair” and it affected her emotionally, mentally and physically.

Payne also said she was disappointed Reynolds was not appointed to a shadow portfolio after the Coalition lost the 2022 federal election.

“I strongly support the involvement of capable women in possible roles in the Liberal Party and have for a long time,” she said.

Earlier, Higgins’ team dropped a bombshell, announcing it had abandoned plans for her to fly from her home in France to give evidence in her own defence.

On Monday, lawyer Rachael Young told the court there were three reasons the plans had changed.

“The first is the defendant is not obliged to go into oral evidence,” Young said.

“The second is … we don’t think we need to call Ms Higgins to satisfy Your Honour as to being successful in these proceedings.

“The third is a matter of Ms Higgins’ medical state.”

Higgins’ condition was to be detailed in confidential medical reports to be filed with the court.

Higgins, who is pregnant, had been due to give evidence later in August. Her decision not to is expected to make the trial significantly shorter.

Outside court, Reynolds’ lawyer Martin Bennett said the Senator wanted the truth to come out after being denied an opportunity to test Higgins during her compensation claim.

“I’m sure what Senator Reynolds would be unhappy about is the contest will not be her word against Ms Higgins. It’ll always be a question of whether Ms Higgins says ‘if I was well enough I could have come and answered these allegations’,” he said.

“That’s unsatisfactory. Linda Reynolds has waited years to vindicate her reputation and this is the day, but these things happen in trials.”

In another development on Monday, Reynolds’ ex-chief of staff Fiona Brown was also excused from giving evidence. She was exempted after psychiatric and medical reports were provided.

Instead, Brown’s redacted affidavit and cross-examination transcript from Bruce Lehrmann’s failed defamation trial against Network Ten and journalist Lisa Wilkinson, and her evidence at his aborted criminal trial for rape, are expected to be used.

Young said she did not want to cause Brown distress or harm.

“The defendant accepts that Ms Brown is unfit by reason of her mental condition to attend or to give evidence as a witness,” she said.

“We support and indeed embrace the excuse of Ms Brown from giving evidence in these proceedings.”

Young said the court should reject or give less weight to some of Brown’s evidence in other proceedings because Higgins wouldn’t have the opportunity to cross-examine her about it and it could prejudice her case.

Another Liberal senator, Anne Ruston, will testify for Reynolds later on Tuesday. Two of Reynolds’ friends, Louise Patroni and Kate Schulze, will also be called.

-with AAP