SYDNEY (BLOOMBERG) - Prime Minister Scott Morrison says the Cabinet member being investigated by police over an alleged rape in the 1980s will remain in the ministry after denying the claim, amid growing evidence of a toxic culture in Australia's Parliament.

The Australian Federal Police said at the weekend it had received a complaint in relation to a historic sexual assault and would be liaising with state authorities. The alleged victim killed herself in June last year, and details of the claims have been sent by her friends to two senators and the prime minister's office.

Mr Morrison held discussions with police about the issue last Wednesday after receiving documents about the claim of sexual assault, he told reporters in Sydney on Monday (March 1).

The member of Cabinet, who has not been publicly identified, "absolutely" denied the allegations, he said.

While "these are very distressing issues that have been raised", Mr Morrison said that "the proper place for that to be dealt is by the authorities, which are the police - that's how our country operates".

He said he did not read the documents sent to him but had been briefed on their contents, and would not be launching an inquiry into the allegations.

Before the claim emerged, Mr Morrison was already under pressure over the workplace culture at Parliament House after a former government media adviser, Ms Brittany Higgins, said last month that she was raped by a fellow staffer in a minister's office after a night of drinking with colleagues in 2019.

The latest claims and the Prime Minister's handling of them will intensify focus on his judgment on women's issues, which was called into question after he said he realised the gravity of Ms Higgins' allegations after discussing them with his wife, who asked him to consider the issue as a father of two girls.

Some female lawmakers have complained about a male-dominated and disempowering culture in the national capital, Canberra. The mistreatment of women in Parliament made global headlines in 2012 when Australia's first female prime minister Julia Gillard accused opposition leader Tony Abbott of misogyny.

Greens Senator Sarah Hanson-Young, who was sent the documents detailing the alleged assault, told ABC radio on Monday that not adequately addressing the issue would create "a serious problem for this government of integrity and trust".

She called for the Cabinet minister to stand aside while the matter is investigated. Sixteen of Mr Morrison's 22-member Cabinet are men.

Mr Anthony Albanese, leader of the main opposition Labor party, said the matter was a test for Mr Morrison and it was up to him to judge whether the minister should remain in Cabinet.

"We need to make sure that these serious allegations, that they are investigated appropriately, and that these issues aren't politically managed," he told the ABC on Sunday.

In the past two weeks, the Prime Minister has faced a barrage of questions in Parliament about his knowledge of the Higgins case and claims that she was not given adequate support.

More recently, former foreign minister Julie Bishop has blasted behaviour by lawmakers that would not be "tolerated in any other workplaces across Australia".

Another lawmaker, Ms Julia Banks, said bullying had driven her to decide to quit Parliament, while a former senator was ordered to pay Ms Hanson-Young A$120,000 (S$123,700) in damages for a series of statements that she said had amounted to sexual discrimination.

Despite priding itself on being among the first countries to give women the right to vote and stand as candidates, Australia has plummeted to 50th in global rankings for representation of women in Parliament, from 15th in 1999.

ABC's Four Corners news programme reported that the alleged assault in the latest case took place in 1988, citing an anonymous letter shared by a source close to the alleged victim.

Labor's Senate leader Penny Wong, who also received the documents, said she disclosed the allegation "to help keep people safe and save lives in the future".

A Newspoll published in The Australian last week showed that while Mr Morrison enjoys strong personal approval ratings after his handling of the pandemic and stimulus injections to buffer the economy, his ruling government remains deadlocked with the Labor opposition ahead of an election due to be held by May 2022.