The 17-year-old has spent the past four years in Canberra schools, but flew out of city at 5pm today despite one of her teachers making an impassioned plea to the Australian government to allow her to remain in Australia to finish her education. They family is scheduled to fly out of Sydney tonight.

She had to leave because Australia joined an international diplomatic offensive to protest against the Syrian regime's brutal crackdown on civilians earlier this week, delivering a 72-hour ultimatum for the country's top envoy - her father - to leave Australia.

Canberra College teacher Judy Talberg told ABC radio this morning that the school community has asked Foreign Minister Bob Carr to grant Mr Ali's daughter an exemption from the expulsion so that she can finish her education in Canberra.

"She's 17, nearly 18, she's a few months away from finishing her Year 12 certificate as well as she's already registered for the International Baccalaureate exam," Ms Talberg said.

Mr Ali's daughter has been studying in Canberra for the past four years, at Melrose High and Canberra College.

"The majority of her education has been done in Australia. She won't be able to fit into a school in Syria," Ms Talberg said

"It's absolutely tragic that she will not be able to continue on her education."

A spokesman for Senator Carr said the expulsion applied to all members of Mr Ali’s family, because their visas were dependent on his. While a family member of an Israeli ambassador had been allowed to stay for six months after that diplomat was expelled in 2010, the spokesman said there had been no request from Mr Ali’s family for his daughter to be allowed to stay. The spokesman could not say whether a request would have been granted, but said diplomats’ family members had also been forced to leave in a number of other countries, too, after the international push to expel Syrian ambassadors earlier this week.

He said Australians were appalled at the massacres in Syria and the expulsions were a method for the international community to express that outrage.

Ms Talberg said the school community had rallied behind the girl in their attempts to gain an exemption, with classmates' families offering to host her, and the ACT education department willing to make her an international student.

Ms Talberg said the request for an exemption for the girl had been denied.

"Everybody's been in tears," Ms Talberg said. "I don't see how this collateral damage ... is going to make any difference to [Syrian President Bashar] al-Assad."

Her school principal, John Stenhouse, said she had a large group of friends and was a model student, ‘‘one that we are very proud of’’.

The school was trying to support her, without making any comment on the situation in Syria or the diplomatic issues around it, Mr Stenhouse said.

"Other people are better qualified to handle that. Our point of view is that it is a talented young woman who this time last week was on track to finish school with a very promising future in tertiary education and that has now disappeared," he said.

She now looked likely to miss out on completing her studies, her school formal and her graduation.

Her father was given until 5pm today to leave Australia, and they began their journey out of the county then.

The rare move to cut official ties followed the worst violence in the year-long conflict, after more than 100 civilians - including women and children - were massacred when government troops shelled the city of Houla.

"Australians have seen the bodies in Houla and they're appalled," Senator Carr said earlier.

"Appalled that a regime could connive in or organise the execution, the killing, of men, women and children."

Mr Ali was understood to have been grimly resigned after the expulsion order was given but not surprised.

The decision to boot out Syria's two diplomats in Canberra is the strongest measure Australia can take, with no embassy in Damascus to withdraw Australia's representative from.