A 21-year-old Israeli exchange student was murdered in Australia while she was chatting with her sister on FaceTime, authorities said.

The body of Aiia Maasarwe was found by passers-by early Wednesday near La Trobe University’s Bundoora campus in the northeast of Melbourne, a city consistently ranked among the world’s safest, officials said.

“This is an absolutely horrendous, horrific attack that has been inflicted on an innocent member of our community,” Detective Inspector Andrew Stamper told reporters Thursday.

“Our presumption is that this was a random attack and opportunistic,” he added.

Maasarwe, who was five months into a year-long exchange at La Trobe, was riding a tram home from a comedy show when she was ambushed about midnight near the Polaris town center.

“(Her sister) heard the sound of the phone falling to the ground and heard some voices,” said Stamper, who would not say whether a weapon had been used.

“Nothing in the victim’s background indicates this was anyone known to her. So yes, unfortunately, the presumption at this stage is this was a random and opportunistic attack,” he said, according to Melbourne’s The Age newspaper.

Known sex offenders in the area are an “active line of inquiry,” he added.

Maasarwe was found partially clad, with her belongings — sandals, a cellphone, book and water bottle — lying nearby, the news outlet reported.

Investigators retrieved a black baseball cap engraved with the number “1986” and a two-tone gray T-shirt that they believe were worn by the assailant at the crime scene, which they described as “very distressing.”

Stamper said detectives were desperate for members of the public to provide information about the shocking crime, which sent shockwaves across the city and Israel.

“Someone in the community knows about this. Someone has gone home on Tuesday night, or in the early hours of Wednesday morning, maybe with blood on them, missing items of clothing. Somebody knows about this,” he said.

The young woman’s father arrived from Israel early Thursday to identify her body, according to The Age.

“We have a grieving family who had to fly halfway across the world under the most horrific circumstances and we want to be able to give them some answers,” Stamper said.

The Israeli embassy expressed its condolences to Maasarwe’s family.

“We express our heartfelt condolences to Aiia’s family and stand ready to support them during this time as our consul works to return her body home to Israel for burial,” it said in a statement.

A La Trobe University rep said the community was “shocked and saddened by this appalling crime.”

“The safety and well-being of our students and staff is of paramount importance and we are providing every possible support following this tragic incident,” the spokeswoman said.

Maasarwe, who grew up in Baqa al-Gharbiyye — a predominantly Arab city between Tel Aviv and Haifa — had studied Chinese and English at Shanghai University before arriving in Australia.

Her uncle Rame Maasarwe, who lives in the US, said his niece loved to travel.

“She’s positive, she likes to have fun, she’s a very friendly person, you know. She’s a good sister,” he told The Age. “I was very proud of her, she was a very good person, a very loving person.”

He said his nephews called him from Israel to inform him about Maasarwe’s death.

“I can’t believe that something like this has happened in Australia. It’s not safe there in Australia? In Melbourne? It’s not safe?” he said. “We think America is dangerous, not Australia.”

Another uncle, Abed Katane, told Israeli newspaper Haaretz that the family was in shock.

“It’s not the type of thing you expect,” Katane said. “She was an excellent student, full of life. She wasn’t in a very dangerous country at all, and yet we are still receiving such a painful message.”

Dozens of locals visited the crime scene Thursday to place flowers and remember the young woman who recently posted shots of her first sunrise of 2019, as well as Australian waterfalls.

On Instagram, she described her wanderlust in her profile by writing: “The best is yet to come.”

With Post wires