CANBERRA (REUTERS) - Australia's Prime Minister Scott Morrison apologised on Tuesday (Feb 16) to a woman who alleged she was raped in the country's Parliament by an unnamed colleague, and promised a thorough investigation into the government's workplace culture.

The woman said she had been raped in the office of Defence Minister Linda Reynolds in March 2019 by someone who also worked for Morrison's ruling Liberal party.

She told local media she spoke with the police in early April of that year, but she decided against making a formal complaint amid concerns about her career prospects. Police in the capital confirmed they had spoken to a complainant in April 2019, but she chose not to make a formal complaint.

The woman said she told senior staff in Reynolds' office of the alleged attack. She said she was then asked to attend a meeting in the office where she says she was assaulted.

Reynolds on Monday confirmed she had been told of the complaint last year, though she denied the woman was pressured against making a police complaint.

Morrison on Tuesday apologised to the woman and promised an investigation.

"That should not have happened, and I do apologise," Morrison told reporters in Canberra. "I want to make sure any young woman working in this place is as safe as possible." Reynolds echoed Morrison in apologising a few hours later.

"Saying sorry is often the hardest thing for those of us who work in this place to say," Reynolds told lawmakers.

"But can I say today, sorry is the easiest word for me to say." Reynolds was the Defence Industry Minister at the time of the alleged rape, and became Defence Minister two months later.

Morrison said he has appointed Department of the Prime Minister and Cabinet official Stephanie Foster to review the process in dealing with workplace complaints, while a backbench lawmaker will investigate workplace culture.

The allegation has intensified pressure on Morrison after a series of allegations of improper behaviour towards women within the Liberal party.

In 2019, female backbench lawmakers said they felt bullied to support a move to oust then prime minister Malcolm Turnbull, while a former female Liberal staff member last year made an official complaint of improper behaviour by then immigration minister Alan Tudge.

Tudge has denied the allegation.