A police officer in the US state of Minnesota who shot dead an unarmed Australian woman last July was charged Tuesday with murder, in a case that sparked an international outcry.

Mohamed Noor shot Justine Damond, a resident of the city of Minneapolis, after she called to report a possible rape in the evening hours, and approached the police car that had arrived to investigate.

"From the short time between when Ms Damond Ruszczyk approached the squad car, to the time that Officer Noor fired the fatal shot, there is no evidence that Officer Noor encountered a threat... that justified his decision to use deadly force," Hennepin County prosecutor Mike Freeman said.

"Instead, Officer Noor recklessly and intentionally fired his handgun from the passenger seat, in disregard for human life."

Noor, who is Somali American, was charged with third-degree murder and second-degree manslaughter, which respectively carry sentences of up to 25 years, and up to 10 years.

The shooting caused outrage in the United States and in Damond's native Australia. The 40-year-old had moved to the US to marry her fiancee whose name she had already legally adopted. Her maiden name was Ruszczyk.

Damond's Australian relatives and the country's prime minister demanded answers -- and protests in Minneapolis led to the resignation of the city's police chief.