The prime minister said it was not his intention to hurt Holgate and he regretted causing her pain.

“That was not my intention and so I regret that,” he told The West Australian on Wednesday.

“But at the same time, the issue here was how taxpayers’ funds were being used in a government-owned company, and as prime minister I have to stand up for those standards and did.”

Holgate left her position after it was revealed she gifted luxury watches to four senior executives as a reward for securing a major contract.

The prime minister had told parliament he was appalled by the purchases and if Holgate did not resign she could go.

Holgate said it was one of the worst acts of bullying she had ever witnessed.

“You would have rather hoped that before somebody publicly hung you and humiliated you, that they may pick up the phone and call you and ask you directly what happened and why,” she said.

Greens senator Sarah Hanson-Young, who is chairing an inquiry into Australia Post, called on the prime minister to call Holgate and apologise for the way she was treated.

“The treatment that Christine Holgate was given in comparison to the backing that the PM has given men who have behaved badly in his own government is just so stark,” she told ABC radio.

“It’s hard not to understand the argument that gender was at play here.”

Businesswoman Lucy Turnbull has described the way  Holgate was treated by the prime minister as disgraceful and an example of misogyny.

Turnbull said the former Australia Post boss should be reinstated.

“She was treated disgracefully and I can’t help thinking there was a bit of gender bias in the way she was treated,” Turnbull told the ABC.

“I’d like anyone else to argue the contrary and point to a man who’s been treated like that.”

The prime minister denied treating Holgate differently because of her gender.

“This was about the issue of taxpayers’ money and I don’t accept there are any gender-related issues here at all,” Morrison said.

Senator Hanson-Young said it would not be workable for Holgate to be reinstated, but called on Australia Post chairman Lucio Di Bartolomeo to be sacked.

There are suggestions Holgate was targeted because she opposed a secret plan to privatise the lucrative parcel delivery service at Australia Post.

The communications union has urged the prime minister to rule out breaking up key parts of the postal service, which Holgate warned would cost thousands of jobs.

“Workers across Australia are now anxious and unclear about where, how and when potential job cuts will be introduced,” union president Shane Murphy said.

“Communities are left in the dark about whether their postal services will continue, the frequency of deliveries and what the future will bring.”