The head of Minneapolis police has resigned following fatal shooting of an unarmed Australian woman by an officer.

Police chief Janee Harteau stepped down at the request of the city's mayor, a day after speaking for the first time about the death of 40-year-old Justine Damond.

Ms Damond, from Sydney, Australia, was shot last Saturday by an officer responding to her 911 call about a possible sexual assault in an alleyway behind her house in Minneapolis.

Responding officer Matthew Harrity had been startled by a loud noise just before Ms Damond approached the police car he was driving, prompting his partner Mohamed Noor to fire the fatal shot, authorities said.

Why did US police shoot Australian woman?

In an announcement on the police department's Facebook page, Ms Harteau said: "I've decided I am willing to step aside to let a fresh set of leadership eyes see what more can be done for the MPD (Minneapolis Police Department) to be the very best it can be."


Ms Harteau, who worked her way up from the bottom of the department to become the city's first female, first openly gay and first Native American police chief, said she was proud of the work she accomplished and honoured to serve as chief.

But she said the shooting of Ms Damond by one of her officers "caused me to engage in deep reflection".

:: Police chief: Australian Justine Damond 'didn't have to die'

Minneapolis Mayor Betsy Hodges had asked for Ms Harteau's resignation.

"I've lost confidence in the chief's ability to lead us further... it is clear that she has lost the confidence of the people of Minneapolis as well," she said.

"For us to continue to transform policing and community trust in policing we need new leadership at MPD."

Police boss apologises for Australian's death

Ms Harteau was on vacation at a remote mountain location for nearly a week following last week's shooting of Ms Damond, a life coach who was engaged to be married.

She faced criticism for not appearing before TV cameras until Thursday.

:: Justine Damond overheard suspected rape, 911 calls reveal

Mayor Hodges announced her nomination of Assistant Police Chief Medaria Arradondo as Ms Harteau's replacement.

But if the move was meant to quell the outcry over Ms Damond's killing, it did not appear to work.

Image: Flowers were scattered on Sydney's Freshwater beach during a vigil for Ms Damond

At a news conference Ms Hodges held to speak about the changes, an angry group of protesters interrupted the mayor within minutes of her taking the podium.

"We're not buying this," exclaimed one protester. "This is just a cosmetic change and we want institutional change."

The protesters were particularly angry about the lack of body camera footage of the shooting, and complained of a lack of police accountability.

"We don't want you as the mayor of Minneapolis anymore," another protester said.

"You're ineffective as a leader."